People who played the real battlefield games (PC Exclusive versions), know how epic they are. Knowing that BF3 is a sequel to BF2, with PC as it's lead platform, and 5 years in the making with a new engine written from scratch specifically for this game...
It's kinda a given it's going to be amazing. A lot of people have been waiting for this game since 2005, and we doubt it will disappoint anyone.
You are right, BF2 was an outstanding game, and that is a huge understatement. That doesn't mean BF3 will be, and if anything, going by the recent trend of FPS games, it won't be, and going by the recent trend of DICE, it won't be. Look at the new MOH when DICE got a hold of multiplayer, and then compare it to your older ones.
That main positive here is, as you say, it is designed for PC, and then ported to consoles, the way it should be. Get the best quality on all, rather than good quality for some, and awful for the rest.
And since when has an engine made a game good? It can provide the features, but those are only as good as the programmer implementing them.