Great value for money, good image quality and decent performance.

I have owned and used the NX10 for 18 months and now the NX11, which is basically the same camera, for 6 months and thousands of photos. Both have been very robust and reliable with no faults.
Image quality is very good, inbetween Sony NEX and Micro four thirds and in line with lower to mid range Canon DSLR's. Some have criticised the high ISO noise which is there, sure enough, but not obtrusive in prints.
Performance is quite good for still photos, not sport/action. Shot to shot time using RAW is 1.8 seconds with AF on each shot. AF is prompt and more important consistently accurate.
Viewing is by the excellent monitor and acceptable EVF. The EVF is satisfactory but not a great joy to use, being a fairly old type with poor shadow detail in sunlight.
Handling is very nice with a small but well shaped handle and thumbrest.
Operation is well thought out and very suitable for the enthusiast photographer who likes to take direct control of primary and secondary exposure and focus variables while continuously viewing the subject through the EVF. This camera's operation is much more photographer friendly than several other compact system cameras I have used, particularly Micro Four thirds.
Several of the lenses for the NX system are excellent. I nominate in particular the 30mm pancake, 18-55mm standard zoom and 50-200mm tele zoom. The zooms deliver much better results than one might expect given their budget price. I like to make very large prints, testing lenses to the limit. The NX lenses stand up very well.

Problems:

None really, the camera and lenses give very consistent and reliable exposure and focus.