I got to play my first game of 7th last night. I'm fairly confident that we actually played 7th, as it was me (an experienced player) vs. a nearly new player (back after years away) so I got to look up every single rule as we played so I could explain it properly, which gave me the opportunity to reteach myself as well.

And yes, it was a success. The new guy will be starting either White Scars or Grey Knights, or White Scars with Grey Knights allies. He suffered a bit over becoming "just another" power armor player, but in the end he decided to go with the models and fluff that spoke to him.

So, my impressions overall are:

1) Not an awful lot has changed. It's still basically the game I learned back when I first started playing at the end of 5th. The game plays very similarly, but...

2) The psychic phase is fun. As the Tyranid player - I don't actually play Tyranids, but that's the demo army my FLGS had - I got to play around with a decently powerful psyker. The Psychic Focus rule gives psykers a nice boost. The psychic phase is a fun tactical experience. My opponent was not bored or turned off by not having a psyker of his own - in fact, he seemed to enjoy managing the resources available to him to pick which of my powers to attempt to deny. Psykers did take a hit, overall, in the sense that powers seem more likely to fail. In this particular game, I lost three powers; two failed to cast and one was Denied. This is far fewer than I usually did in most games of 6th with a Ld 10 psyker.

3) The changes to shooting are very intuitive, and my new player opponent understood them immediately and began making smart choices right away.

Of course, nobody here was trying to break the game. It was 500 points, fairly generic Space Marines vs. fairly generic Tyranids. I played pretty hard, and don't think I would have done much of anything differently vs. another experienced player (except, you know, bring my own army that I actually know what I'm doing with).

It was a fun game. No complaints so far.