I decided I should add some comments to this thread because I too have purchased one of these. $400 shipped for a dual extruder was just too good to pass on.
Hardware wise, mine has the same issues that have been mentioned by others in this thread. Screws all over the machine were loose. Left extruder needed to be adjusted to level. Bed temperature isn't accurate. Easy fixes for most, but for the bed temp issue, I had to resort to cheating. I simply set the bed temp to 130 if I want an actual temp of 100. I did install a glass bed above the aluminum one, I decided that was an essential upgrade if your printing anything beyond PLA.
Issues that I still could fix but probably won't are the poor extruder design (my 1.65 filament extrudes, so spring loaded or not, it does work).
Worst issue is of course the software. Even after you upgrade to Sailfish (7.7 on mine currently) you still stuck with a printer that can't use gcode directly. This leaves you with several options, some far more painful than others. If you can live with the Makerbot Desktop 2.4 that comes with the printer, your all set. It integrates perfectly with Meshmixer which will provide good supports and all you need Makerbot Desktop to do is slice. Makerbot Desktop "expert settings" are completely hidden. You need to create profiles to get the most out of the software, but there are tools to help you do so.
If Makerbot's software isn't good enough for you, that is where the problems start. While there is a converter (gpx.exe) you'll probably find that getting any other program to slice and position on the bed properly is going to take a lot of time and effort even after you follow one of the many guides others have written. For myself, I'm sticking with Makerbot Desktop for the time being while deciding on Simplify3d. Your other option is an electronics upgrade, which isn't cheap or easy.
