I have the Makerbot Replicator Mini and I wouldn't really recommend it
(can't complain since I got it for free). When something breaks you need to get it repaired and that's expensive. These mechanical things break easily and I had multiple times where the extruder jammed and we had to take it apart to get the little piece of plastic out.
It's very useful to print joints or stands, don't expect very precise results, the surface is very jagged. If you can already 3D model it's a huge plus, then you can make custom stuff! (I can't) There's a ton of models you can just download and print though e.g. at http://www.thingiverse.com/
I've printed small flower pots and cookie cutters and they came out nice (again, when high precision is not required). Filament costs are *very* reasonable when you don't buy directly from Makerbot.
Ah and printing takes a long time. For the flower pot which was about the maximum size the printer could print, it took a day. Depending on the printing surface, you also might have to split bigger models into multiple parts.