Two months ago I gained access to a MakerBot Replicator 2X, their top of the line 3D printer. Between writing, work, and kids, I haven’t been able to use it regularly, but I’ve spent several large blocks of time with it.

I’ve used it with both ABS and PLA plastic, including designs I’ve downloaded from Thingiverse, as well as creations I’ve made coding with OpenSCAD, a programming language for 3D stuff.
It’s been both awesome and kind of sucky.
First off, it’s undeniably cool. I’ve been using it mostly in an open work space, and it attracts passerby like crazy. The process of printing is entrancing, and it’s easy to spend thirty minutes just watching it construction a shape layer by layer.
When it builds something successfully, it’s awesome. I can put a simple cube into someone’s hand, and they marvel at it. My kids beg for me to print them stuff, my wife is wearing a 3D printed bracelet, and we’ve got stacks of nested boxes all over the place.
But it’s not easy to use. In fact, it bears a lot of similarity to operating an offset press, something I did in high school. It requires training, an understanding of the idiosyncrasies of the machine, and the ability to troubleshoot myriad problems. 
Other periods of computing were like this: connecting with modems in the early 80s, managing memory within the 640KB limit of MSDOS. I’m sure 3D printing will get better, because the promise is so great, but it’s still very much in its infancy.
For example, the build platform requires a very precise calibration to ensure the print heads are the correct distance above the platform, especially with ABS plastic. This process requires frequent recalibration, as the repeated heating and cooling of the platform seems to throw off the calibration. 
ABS plastic is also super-smelly, throwing off all sorts of toxic fumes, so I switched to using PLA plastic. But for PLA, the 2X seems to have problems feeding the plastic into the print heads. If it sits for even a minute with the heat on, or if it prints a piece where the plastic is feeding slowly, then the 2X suffers from something called heat creep, where the PLA plastic slowly softens such that the feed drive doesn’t push the plastic down. Few things are more frustrating than having a nearly complete model that’s been printing for an hour suddenly stop building, because of heat creep. I have more abandoned PLA builds than completed ones.
As a result, I’ve tried to play with printing temperates and speeds and added supplementary cooling fans. I’ve also become attuned to the sound of the feeders losing their grip, so I’ll quickly add manual pressure until it feeds correctly again.
Hopefully we’ll see a future generation of 3D printers that includes automatic calibration of the build platform (should be relatively simple, and more accurate than the manual process). And print heads that manage the temperature, feed pressure, and cooling to prevent such feed problems.
I’ll follow up with some photos soon.