I read that DICE said that the console version of Battlefield 3 will "Blow BF:BC2 visuals out of the water" So I don't really know, I mean, there close to launch date and they barley released any console footage (aside the one from Late Night with Jimmy Fallon.)
All I heard from the specs was it said to have DX 10.1 and 6gb of flash ram :\
The iPhone usually has allot of indie games to play, while the 3DS has full retail games, so I think it's not worth comparing. IMO
Sound? I remember in MW2 the sniper "intervention" sounded like a belt being wiped on a hard surface O_o