Pardon my semi-necro, but I have to say as someone who played only one full game of fifth edition, I don't mind sixth too much. Yes the warlord thing is kind of a groan inducer, but i'm hoping *fingers crossed* that a FAQ will save the day on that one. Additionally, obviously the "psychic" specialties are kind of an untested element at the moment, but it could be cool. World Eaters, you got hosed, though.
Maybe I'm biased because I've got a tasty Deathwing army (pure luck, btw) and didn't get hardcore butt-slammed by 6th, but I'm already noticing people quieting down with the hate and starting to discuss new strategies and possibilities.
Also, the allies thing is what you make of it. Someone somewhere might try to abuse it, but as most of the support posts have said, it's a game! If someone is being a douche, don't play it with said doucher. Find someone willing to not be an ass. As someone with Space Marines and Chaos Marines, I'm pretty obviously set up to nab some IG if I wanted to, but I'm pretty well off sticking to what I have until I've got double digit games in on each army (see sig if you must know). Not going to be "that guy" who tries to mix and match obvious tardistry (ChaosTau??? dafuq?) just so I can find some way to win games...not that I see that list running the table, but you get my point.
Finally, screw you, Matt Ward! Stop bleeding cobalt and show some love for the rest of the races.
"We are the Necrontyr. We are legion. We claim dominion of this world... Surrender and die."
Total W/L/D count!!!!
Dark Angels, 3rd company