I've spent a little bit of time with the Sony NEX-5N [$699.99 with 18-55mm lens], and this is what struck me about it so far:
It's small! It's not tiny, and I knew it was small, but still, I was surprised how thin the body is!
The size does make me worry about attaching a large lens to it; especially if I want to put it on a tripod. I might have to get a lens/tripod ring...though I see they can be expensive!: Canon Tripod Mount Ring D for IS 100mm F2.8 Macro Lens. Anyone got a source for cheaper third-party lens tripod mounts?
People have been talking about the build quality of the NEX-7 [$1,199.99 body only]; it's supposed to be pretty impressive. But I'm quite impressed by the quality of the NEX-5N, especially when you compare it to some consumer camcorders that cost twice the price (i.e. the Canon HF-G10 is very plasticky and cheap by comparison.)
Speaking of camcorders, having been spending so much time with them recently, I sort of forgot that the NEX-5N is a still camera. And I was almost surprised by the fact that it comes with a separate charger and you have to take the battery out of the camera to charge it. Most consumer camcorders come with a charger that charges the battery in the camera. Odd how that works.
The screen is really good. One of the things I noticed when playing with it is that it seemed to be much easier for me to tell whether something was in focus by looking at the screen; or at least I have that impression. I'll have to see how it works in actual operation, but it certainly was better than using the LCD screen on the back of the Canon 7D.
Lens: I'm learning to like the 18-55mm lens it came with. It seems smoother to zoom than the only other E-mount lens I've spent any time with; the 18-200mm.
Focus Peaking! It's almost a shock to find that this consumer still camera has both color peaking, and doubles the image while you are focusing. Those features have only recently been showing up in consumer camcorders. I really like this.
Menus and things. The menu system has been derided by some as being consumerish. I have no real opinion at the moment; it just seems like something new to learn. What did surprise me was the fifty or more icons that decorate the LCD screen while the camera is in operation! I wonder how many users of the camera will know what half those icons mean!