The Register have reviewed it and given it a big thumbs up: Google Nexus 7 Android tablet ? Reg Hardware
TBH, as it has GPS built in I think it will be the ideal travelling companion for use as an in-car sat-nav/MP3 player and be able to get your emails at the other end, as well as providing for in-flight entertainment when travelling on the cheaper airlines. I spent almost 20 hours as a 'guest' of American Airlines last month and would have killed for one of these. My advice is to load up your phone/tablet with some movies if you are going to fly with AA!
I wouldn't want 3G (data) or any phone connectivity as I could always slave it through my phone, but as a companion device I'd be more than happy with one.