It's very annoying to have a queue pop on the last boss, meaning you'll have to queue again, especially when you're sitting through 5 queues for 5 different LFRs (or more with multiple toons.)
However, it was more annoying to join a 0/3 group, have multiple people leave after boss #2, and simply be unable to get a full group to attempt will ofthe Emperor or Garalon, no matter how long you waited. Can't port out and quest while you wait, you're in a raid group. Can only hang around doing nothing in the dungeon until a critical mass gives up, so you leave, queue again, and start the dungeon all over. At which point the same thing happens after boss #2.
New method isn't great. But the old method was worse.
A change I'd love to see is the ability to queue for LFR, and have that queue remain while you switch toons and play someone else. Queue pops, and clicking accept logs (and maybe hearths) your current toon, and you're on queued toon doing your dungeon. With queue times of 2 hours+ for me at some points, this would help a lot. Instead of spending that two hours aimlessly flying around doing random pet battles, because I don't have quests, dailies, or farming profs to do on that toon, I could spend the 2 hours leveling an alt, doing dailies on someone else, etc.
What would also be very helpful, is if that you queue for 2 roles, you can select any of those specs as the gear table you'll get. It wouldn't be a case of queueing as just damage, then getting tank gear, but instead queueing for damage & tank to make queues shorter, without losing the ability to get your gear. For a pally tank to get the best 476 tanking chest, they need to run MV part 2 as DPS (will of the emperor tank chest seems to be budgeted lower than spirit kings 'dps' chest, plus the dps chest has a better type of stat, too). To get their 476 sword & board, they need to either wait a long time as a tank, or queue as both, and if they enter as dps, do it badly on spirit kings & elegon by staying in prot spec.