Mostly the lack of teamplay. Ppl mostly runs around cod-style without any tactics. Hardly no one revives. No teamplay with gadgets. Like the SOFLAM + Javelin combo in BF3, for example.
I really hated Battlelog on it's release but after some time I loved it. You could spend hours checking stats, preparing loadouts, checking missions, awards, ribbons, assignments, dog tags, unlocks, progress level of each class, progress level and editing of your plaoton and opening battle packs. But most importantly, a very detailed and complex server browser, where you could check your server/matches history, adding favorite servers etc.
Since BF3 I've really missed properly made maps for rush mode. Nothing beats an intense rush mode map. When the balance is perfect and people really are forced to teamplay.
The only thing that would make me instantly preorder the game is mod support.
