A few things that I really like about this 3D printer:
(1) The display unit allows printing without being connected to a computer. All the initial printing I did was using the USB connection to drive the printer directly from my laptop. This was kind of a pain, as the laptop was then tethered to the printer for the (fairly lengthy) duration of the print. Now that I have the contrast set properly on the display unit, I can put the GCODE on to a micro-SD card and start the print up without connecting the computer. Very convenient.
(2) Upgradability. People who bought earlier versions of this printer were able to download and print their own upgrades, or order just the necessary parts. I figure things will be changing rapidly in this field, and hope that with this printer I can stay near the front edge of the home printer field with relatively little further investment. I also liked that there were standard printable accessories on the web site, and user-contributed improvements. Shown below is an improved Z-axis limit sensor fine adjustment device.
(3) Openness. It's using all open source software. Repetier Host, Skeinforge, Slic3er, etc. No proprietary filament needed, just standard 1.75 mm PLA or ABS.
(4) Design. More and more I'm coming to appreciate the design of the printer. With the version 3.0 the manufacturers have really worked out a lot of the design kinks from the earlier versions, and have replaced the previous printed parts with mass produced injection molded versions. The solid metal frame seems very sturdy and provides a large build area. The hot ends also seem pretty reliable. Of course, I don't have a lot of different comparison points, but I'm pretty satisfied with what I've got.
Finally, I'm really glad that I opted for the kit and built this thing myself. I think if I had bought it preassembled I'd be a lot more timid with it, but since I put the whole thing together I have a lot of confidence that I should be able to fix anything that goes wrong with it.