I purchased my i5, 4GB, 160GB SSD model directly from Lenovo.
The listing here indicates the X1 has a 160GB hard drive, which, technically, is incorrect. The X1's come with a 320GB spinning hard drive or 120 or 160GB solid state drives. Let me say this as emphatically as I can without using all caps and exclamation points: Do not buy a laptop with a spinning hard drive unless you absolutely positively have to have 300GB (or more) of data on your drive at all times. If you think you need this much storage then also purchase a 40 or 80GB mSATA internal drive and use that for system/program files. Apple was able to run an old processor in its macbook air's for years because the speed of the drive, being solid state, was so incredibly fast it more than made up for the slow processor.
The X1 with the SSD is a speedy machine. Reviews compare it to the macbook air but the specs of the X1 (double the RAM, full power i5 chip, upgradeable mSATA and main drive) make it more of a competitor for the 13" macbook pro. The mac (13" pro) has a better screen and battery life; the lenovo is lighter without the slice battery, with it the weight and battery life are about the same for both machines. The X1 and the 13" pro are running the same integrated graphics although the X1 has a marginally faster processor.
The Gorilla glass screen (made FOR Gorilla's, not BY them) is supposed to be impervious to the pointed end of a house key but what that means for regular hominids is not having to look at a screen covered with marks from rubbing against a dirty keyboard. It also means the screen is very easy to clean with anything you've got laying around. There is a video of the X1 being dropped from 16ft and then booting up and playing Angry Birds, in short, this is a solid and durable machine.
If you have read other reviews of the X1, you'll know the two main complaints are about the battery life and the glossy and comparatively low res screen. I've had my machine for about a month and I get between 3.5 and 5 hours depending on what I am doing. I thought of purchasing the slice battery to double that time but I don't think I will. The X1 comes with a quick charge battery. That means that in 30 minutes you get 80% of your charge back. In real world terms, ten minutes of charging time gives you about an hour of use. The ultraslim 90w adapter from lenovo weighs less than the slice battery and takes up about the same space. If I had a regular schedule that required me to be unplugged for 5-8 hours a day then the extra slice battery would be a good choice. The quick charging, however, means that I can carry the charger and not ever have to worry about running out of juice as long as I can get twenty minutes of plug time every four hours. Also, using the machine while charging does not slow down the recharge time.
I like the 13.3 screen on the X1. If the Gorilla glass were available in matte then yes, that would be preferable but I am willing to exchange the susceptibility of a matte screen to marking for the permanent newness and easy clean-ability of the glossy gorilla glass. I carry my laptop around primarily in a messenger bag and so it spends a lot of time being mashed, compressed and bumped. After 3 months of this (ab)use, I typically end up with marked up screen. The lower resolution of the X1 is actually easier for me to work with as most of my time on this machine will be writing or reading. Some reviewers have noted a screen door effect on the screen but I can only see that at closer than 5 inches.
Overall this is my favorite laptop ever and I did choose it over the macbook air mostly because of the keyboard. I also like the boring matte black almost soft finish on this machine. The trend towards machined aluminum, while visually distinctive, is, I think, less comfortable to hold and type on than a coated metal or plastic finish. Also, the hinge for the X1 is located high on the back of the machine. This means the bottom edge of the screen bezel doesn't rotate down when the screen is opened. When looking at a mac and the X1 side by side, the bottom of the screen of the X1 is almost an inch higher than the mac which for me is less distracting when typing.
If you can spend about $1500 and prefer durability, processing power and the best laptop keyboard ever to battery life, high-end graphics performance and screen resolution you won't be disappointed with the X1. Get the i5 or i7 with an SSD.