I've had a smooth connected experience, but just a couple hours ago, we were four of my guild doing a dungeon, and we got hit by a lag spike (and wiped), but one of us was disconnected - and found herself with a 3000+ queue, so she wasn't going to come back.
The queues themselves have been smooth after their server revisit on Wednesday. The only time I got hit by problems was when three of the servers on my datacenter shat themselves, and everyone tried to reconnect at the same time - that's when we got 2002 and 300x for a while. (I was on discord, and a friend said "uh uh, everyone got booted from Louisoix, Moogle and Cerberus" and I immediately replied, "time to launch additional clients for the queue". Got 2002-ed 3min later)