As for the previous comment "There's plenty of excellent FPSs out there that are way better than Battlefield and CoD." Don't confuse YOUR OPINION of games with a definitive 'better' or 'worse'.
Parroting this in every post you make never gets old, really we never tire of hearing it Uh oh, I said we!
As for unlocks, they're fine when they're balanced but BF3 has very poorly balanced unlocks overall that create a real disparity between those with and without.
I'm someone who despises MMOs and other "play a 100 hours or you're not allowed to be good" games- I have to admit BF3 is somewhere in the middle. After a little less than 20 hours in I have the SCAR H with some goodies, enough goodies for the M249 to make it work and the mortar for points grinding. I broke 2000 points a round instantly after getting the mortar.
Most mechanics-changing unlocks come pretty early compared to past BF games and especially compared to MMOs and the like.
They're going to nerf the silly ones in this patch so there will be even less to complain about.