I bought it the other week, still getting to know it but no problems so far and very happy with it.
I've emailed support twice, and both times had my question answered within a couple of hours (of course outside US office hours it's going to take longer). I don't know whether it needs an internet connection to first activate the program, but it certainly doesn't require a connection to work after that.
I bought it for the ability to apply different slicer settings to different parts of a print (different objects on a print bed, or different parts of the same object).
Tim
Printers:
Prusa i3 (plywood box frame)
RAMPS 1.4 and Arduino Mega
Mendel 90 (sturdy)
Smoothieware
My RepRap Blog