LFR second half is no longer than first half. still done in 20 minutes if you'r group does it right (and isn't afk tabbed out on trash complaining about it on forums)
20 minutes maybe a bit short for both trash and bosses, even for a geared group at this point of the patch. 30-40 maybe, but not 20 minutes.
The issue I have is the sheer amount of adds. Yes Ji-kin's adds are the most pain in the rear end. I've died numerous times that the snail is targeting a range and all of a sudden switch to me who is in melee and 1-shot me. The Maggots need a better way to pull them out under the ground.