I don't know if 7th is the best edition or not. I can tell you, my personal motivation to play is at an all time low. I'm more psyched about painting up a single BFG ship and a farseer conversion model for my Rogue Trader RPG session that I'm flying to the east coast to play in than I am to drive down to the local GW for a game of toy soldiers. My friends and I are slowly selling off our apocalypse gear - he just ditched two warhounds and a reaver.. I'm going to probably put a phantom or two on ebay shortly - along with some of my Blood Angels since I can't seem to be able to field the army I want without going Unbound - which takes me to one of my critiques of 7th....
...They basically gave you an out as a player to be dorky cheesemonger with your army list and still be able to play it. I tried playing unbound once - and it was only just to get an extra spirit seer in an Iyanden list but the reaction was one of "Unbound? Oh... you're one of those guys, well let me go change my list a little bit." Yeah, I can run unbound, but no, its not socially accepted.
As an Eldar player, the psychic phase sucks. First, random powers are STILL terrible. You can't reliably get buffs casted and its way too easy to deny a power. last game with my eldar, with 6 warp charges on the table, I successfully cast two powers the whole game against Necrons... NECRONS!!! This isn't an isolated incident. Since I don't spam wave serpents I actually need my psykers to buff my dudes, and it just doesn't happen more often than it does - and it makes me really just want to give up. Its tough to decide whether I hate the psychic phase more, or the maelstrom missions more....
I lost a game simply because my opponent managed to draw 2 "Secure objective 4" cards on the last turn that he happened to have a tomb spider hovering over it. The randomness of the cards leaves no overall strategic goals, its like 40k for ADHD kids and its terrible IMO.
So overall, while there are some mechanics of the game in 7th that are improved over the previous version, I'm still pretty blase about it and I'm jonsin-aching to go roll some D10's in Rogue Trader.