This is my first projector, so I cannot really give too technical of a review. However, here are the things I've noticed in the short time I've had it so far...
Like others have said, it's bright. I can use it in the middle of the day with blinds open and see perfectly fine. From what I understand, the image will gradually get dimmer the more hours it has, but for now it's superb.
It's very easy to use. I've never operated one before and was able to use it right out of the box. Plugged it in, connected my ps3 or laptop, and turn it on. It automatically detects everything without issue.
The image can get quite large. So far I've been using it to generate an image about 8 ft wide with a good picture. The projector is 14ft away from the wall. Definitely much larger than any LCD or Plasma!
I purchased this projector for a short term relocation. I didn't want to have to ship a TV and figured if I bought a projector I could take it home with me in a few months. It's easily portable, and this one comes with a case (unlike some others. I also looked at getting the Optoma hd66 which is in the same price range, and I don't believe it came with a case and the viewsonic had a few more features).
I haven't used 3D yet since 3D glasses are still quite expensive, but one day I hope to try it.
If the lamp lasts 4000-6000 hours, I will be perfectly satisfied. That should give me several years of usage, and at that point it'll be time to upgrade anyways (technology flies these days)! Or, I could replace the lamp, although I still haven't found any bulbs online yet. I use ECO mode as well, and the difference in ECO mode and standard is hardly noticeable. ECO mode is plenty bright enough.
UPDATE: Be sure to check the contrast settings if you don't see a proper picture. The contrast setting automatically switched to 0 for HDMI input somehow and I almost returned it thinking the jack had become defective (only saw blank screen). I'm not sure why it changed, but be sure to check if the image seems off even if you didn't change anything yourself.