This is a laptop for people who want to get things done.
The X121E excels in two areas: performance and portability.
The i3 processor it packs, despite being on the lower end, is easily fast enough for productivity tasks and even some image editing. It runs AutoCAD faster than my Dell Precision, which has the previous Core2 processor at over 2ghz and it handles browsing, MS office, and Photoshop with equal aplomb.
The chassis is thin and light, though it can't compare to the newer ultrabooks. Battery life seems to be at about 5 hours with usable brightness - more than enough for me.
The rest of the package is a bit mixed. The keyboard is excellent, with the action on the keys being satisfying and all of the right functions featuring enlarged keys. The trackpoint works as well as in any other Thinkpad, but unfortunately the touchpad with its integrated mouse buttons is too small and strangely textured. If you can't get on with the traditional Thinkpad nipple, you might have to invest in an external mouse.
The display also isn't great shakes, with an uneven backlight and poor viewing angles, but that applies to just about every laptop, unfortunately.
All in all, the X121E offers fantastic value for money and is one of the most capable ultraportables I've used.