I've used a NEX-7 for a couple of years, alongside my Nikon SLR equipment. Unlike many on this thread, I think it's a killer camera, for most uses.
I also think that after a slow start, there are now some excellent autofocus lenses available, including some fine Zeiss optics and the Sigma 60mm, which is stunning. The NEX-7 adapts well to other brands of lenses for manual focus. It has great build quality, is quiet and has no shutter lag. The built-in viewfinder is good. The tilting LCD is top notch. I find that the camera fits my hand perfectly, which is important to me. I like the ability to move autofocus to a button on the back instead of the shutter release. The files at ISO 100 are stunning with good lenses. They can make very large prints.
There are some downsides to the NEX-7. So-so focus speed. Grainy files above ISO400 (although the grain is actually pretty nice and doesn't wreck detail until higher ISOs). Crappy menus, partly redeemed by lots of button customization. Corner problems using super wide lenses of certain types. I expect the new A6000 will help with most of these.
If "street photography" means quick autofocus grab shots, I'd go with something else--probably one of the fast-focussing Oly or Panasonics. But for less hectic street work, travel, portrait, architecture and landscape, the NEX-7 is a worthy choice.