Overall mine has been better than it was at 3.3.5, although some fights are relatively close (a couple % points more generally).
Last raid week (two weeks ago, actually - didn't raid last week) I went through as fire (non-mastery/ffb) and did relatively well, I believe averaging about 12-14k dps per fight (depending on the fight, of course). Last night we went through 10/12 heroics (saved H sindy + lk for thursday) and I was hitting higher numbers with arcane (reforged a lot of stuff into mastery, pretty much anything that had haste on it) and my low-end dps was around 15-16k. On Saurfang I lead the raid with about 22k dps (lol 97% arcane blast, if I would have gotten an innervate I could have went 100%!), and on BQL I got the 3rd bite and hit 28k (first bite was a fire mage that pulled close to 35k).
Arcane blast crits (yay fun): highest normal fight crit was ~100k. highest I've seen so far was 155k on BQL after the bite. average crits are around 40-50k.
While arcane is super easy, it isn't really 'fun', but I know that will be changing come 4.0.3 when we are leveling and our combat ratings get nerfed. Fire will take a serious hit for the same reason.