A couple of corrections:It's important to note that the sensors on NEX cameras aren't 4/3rds sized - they're APS-C, which is about twice the size of micro 4/3rds, but about 2/3rds the size of a 35mm frame.
I think this about covers it. The NEX is a great camera, and I highly recommend it for the majority of people However, I know that it compromises a few things in order to be compact. The NEX-7 is a bit of a step up and an attempt to appeal to a more demanding crowd.I have been primarily shooting with DSLRs for the last 5 or 6 years. Much of the shooting that I would do with a compact camera would be in low light, so I've been waiting for an affordable APS-C format compact. The high ISO quality of any format smaller than that hasn't been satisfactory. I went with a NEX-3, because it's also important to me that my compact camera be affordable, and have been shooting if for a few months. It has been a joy in the situations where I've always wanted a compact, but felt like I had to carry a DSLR: family activities, wandering around, out and about with friends, etc.... It's not going to replace my DSLRs for most of my personal and client work.