I have the NEX-5, don't find it dumbed down, the only really difference is that the mode dial is on the screen, not on the top plate. No biggie.
I use it with a Nokton, and the quality is awesome. I also have the 16mm, the quality is, well, meh, particularly wide open, it's actually quite soft.
I sometimes think I want a G1 or G2, as the EVF is so good, but it's the crop factor that always put me off.
Before the NEX, I had the GF1 with the 20mm, I miss the lens, but not the camera.
MT