I've finally received the Rift I pre-ordered 6 minutes into launch, and my first experience with it blew me away.
Having read every article, every review, and having a dedicated tab in Chrome open to the Oculus Subreddit, reading all I could before I finally got my hands on my own unit, I didn't expect to feel the amount presence that I did. I was worried about the negativity towards the FOV (field of view), the resolution, and the "godrays" (crepuscular rays). I was preparing for disappointment, and I'm glad I was, because I was able to appreciate it all the more. I've now also had the experience of thoroughly testing out the HTC Vive, which I also pre-ordered and received the same day as the Rift, so I can offer some comparisons as well.

Immersion:
It really is difficult to describe quality VR other than to say that you really feel like you're there. There's a demo that places you atop a skyscraper in a busy steam punky city filled with a zeppelin, a hot air balloon and bustling below. There was so much depth, the scene just felt enormous. I really felt that great expanse. I felt an equal amount of presence in the Vive, if not more thanks to its out of the box roomscale experience. Walking around physically adds a great deal of depth. The Rift is a stand-up or sit-down experience for now, with touch controllers and a second senor to come later this year. That will equal the playing field for a roomscale experience.

The FOV:
The field of view is difficult to measure and convey. It's the center of many debates, and there is a lot of misinformation about this, and many inaccurate image representations and measurements. It's going to also differ from person to person, based on how close your eyes are to the lenses, and whether or not you wear glasses, so I'll just stick to perceived comparisons with the Vive. Both the Rift and the Vive have very acceptable FOV's. If you'd like to get an idea of what it's like wearing one of these headsets, take a toilet paper roll, cut it in half, and look through them with both eyes. It'll give you a very rough idea. It's also comparable to wearing ski goggles. The Rift has a very comfortable FOV, and very similar to that of the Vive, but the Vive's does appear larger. The Rift's FOV feels like a squarish circle, whereas the Vive looks like a much more uniformed circle. If you mod the Vive you can also eek out a few more degrees, increasing the FOV just a bit more. I could also see the ghosting from the edges a bit more so on the Rift, due to imperfect stereo overlap. I can see this on the Vive as well, but due to the Vive's lens shape it's a bit less prominent. Easy to ignore on both devices... and mild. I'm just being thorough.

The resolution:
The Rift has a resolution of 2160 x 1200 pixels, as does the Vive. 1080 x 1200 px per eye, but because the screens are so close to your eyes, and because of the way the image is stretched by the lenses, you're seeing something that looks closer to a 720p image if not somewhat less. It's definitely not as sharp as a standard monitor, but it's very acceptable. Go in with low expectation and expect to be impressed. When I first stepped into Oculus Home it was beautiful. Comparing resolutions to the Vive, the Rift comes out ahead. The Vive trades FOV for a bit of a hit to the resolution. Both are beautiful, but the Rift is noticeably clearer. Some text that was easily readable with the Rift was difficult to make out on the Vive.

Godrays, halos, and flare:
Okay, here's where it really disappoints. The godrays and halos are in fact present and very distracting in a lot of scenes. I found that it took some playing with the position of the headset to minimize them. Positioning the headset slightly higher than what felt natural gave me the best results, but they were still very present. There are of course a lot of games and experiences where they're a non-issue. I didn't at all notice them in brightly colored scenes, or in 180 / 360 degree videos. They were most present in high contrast scenes, extreme during menus, and very distracting in experiences taking place in space, or in the dark. Watching a video in a VR theater was nearly impossible. I'd quickly end up with a headache due to the halos, which is similar to having a flashlight shine through a pair of binoculars. It's caused by the many facets of the Fresnel lenses used by both devices. Because the Rift has more facets, it's more of an issue. Both devices suffer from this problem, though the Vive slightly less so.

SDE (screen door effect):
Because of how close the screens are to your eyes, and the current resolution limitations, VR has to deal with SDE, which is what it sounds like, like looking through a screen door. Thankfully, the Rift's SDE is so minimal it's hardly noticeable. It's there, and you can see it if you look for it, but it's just so faint, and easy to ignore. The Vive's SDE is somewhat more prominent, again a trade-off of the larger FOV. There's a noticeable difference between the two, but both are acceptable. It's not a deal breaker for either, and you'll quickly ignore it when you start playing.

Tracking:
Tracking is very good, and surprisingly accurate. I felt absolutely no delay between my movements and the motion inside the Rift. And the motion inside the rift is perfectly smooth. There's no unnatural blurring, or any other sort of issues.
There are IR sensors all on the front of the headset, as well as the back, so with one sensor you're still able to rotate yourself fully and still be tracked properly.

Comfort:
The Rift has comfort down. Keeping the strap somewhat loose and having the straps hug the back of my head I can wear it four hours without any discomfort. If it's hurting your face or leaving an impression than it's too tight. The Rift is considerably more comfortable than the Vive in my opinion. Although there are ways to mod the Vive for more comfort, the Rift is much lighter, and so much easier to put on and take off, especially considering the Rift has built in headphones, whereas the Vive does not.

Audio:
The built in headphones are really very decent. Audio is very important to me. My main headphones are AKG K712 Pro's, and I also own a pair of Hifiman HE-400i's. The Rift has on-ear headphones that are very comfortable and sound great. It's something that I very much would have liked to see from the Vive. The Rift's headphones can be removed as well if you wanted to use your own, or they can be flipped out of the way. Their position is easily adjustable.

Other thoughts:
Both the Rift and Vive have their strengths and weaknesses. The Rift has the advantage in terms of optics. It looks clearer and has a more relaxed focal point. That is, my eyes can wander off center a bit before it becomes blurry, whereas with the Vive when my eyes wander the image becomes blurrier sooner, though, removing the Vive's face pad and modding it with your own thinner pad will improve this drastically, while also increasing the FOV. Though the Rift and Vive have the same displays, they use different lenses, and as such have various trade offs as detailed above. If you need roomscale VR now then you'll want the Vive. If you can wait, the Rift will be releasing its touch controllers later this year with an additional sensor, which will allow for roomscale as well.

Having said that, overall, I'm very impressed given the current limitations of technology, and though I'm looking forward to improvements in resolution and hopefully a fix for the godrays, I see no reason to wait, other than because of its limited availability. VR ready now! ;)

These worked perfectly for me. Came with everything I needed to kick-start my VR experience. Occulus has a nifty application store and a bunch of apps that work for the headset. The sensor worked well. I wish there was a way to set my screen in any orientation I wanted. IE calibrate the screen for sideways viewing especially for beds since my room was a BED-room.

Downsides:
-I had VR sickness probably due to me focusing on the pixels. FYI I do get motion sickness (sea mostly).
-VR technology is super new and these headsets make all my games seem like they are in 800x600. This is b/c the headsets are so close to your eyes.

This is an amazing product. Just as an FYI, some do work better then others. I bought one when it first came out and had to return it due to display issues. I have a DK2, and was planning on just sticking with that until the next generation of headsets was on the market. With the recent bundle deal, I couldn't resist buying it again. I am SO glad I did. It works so much better then my DK2. The first CV Rift I bought had awful God rays and one lens was tinted red while the other was not. It was annoying and even gave me headaches. This new one is a huge improvement over the first one I bought. The God rays are much improved, and there is no discoloration.

It truly is amazing technology and Rift does a fantastic job in all aspects. The VR Headset is fairly easy to get up and running and once you enter the VR Realm you don't want to leave. A good variety of games and experiences are available even though the tech is new. Where Oculus Rift seems to rise above the competitor is that the headset feels lighter. and less encumbering, and has one cord to the computer. The headphones sit well and have very decent sound. Once you're in the VR world, it all comes together in a spectacular way, you can visit nature, museums, and even be part of films.

VR is great. This is a great headset. Quality build, comfortable, the earphones are not in the way and offer good enough sound quality. I store this on a black mannequin head and base, and the cable stays out of my way. This came with the Oculus Touch and two "cameras" which are actually sensors.

If you haven't tried VR, you should. Check your PC to ensure it meets the VR requirements (there's an app on OR website that will check it for you). You will enjoy this experience.

Pros:
I just about fell out of my chair the first time I tried turning in Elite Dangerous.

Cons:
The image was blurry and poorly resolved in just about all the positions I tried wearing it. Ghosting was pretty noticeable. Glare was also an issue. Installing the software took about 9 hours, 15 of which was actually installing, the rest was downloading, my internet connection was not the bottleneck here. Oh and you can't use it at all without the software. Eventually returned it.