[Galaxy Tab 2 (Unified 7" + 10.1") Android Developm] JoeSyr:
I loaded the 1/29 build last night on a clean install (with the latest Nano PA Gapps and SuperSU install zip, all on Andi's latest TWRP build). So far so good, here's a few observations:

-The first boot took a pretty long time but from what I've read this is normal. I didn't reboot again until the next day but for the second boot, the bootanimation never loaded, it just went straight from the brand logo to the launcher, long black wait in between. After that, all fine. Later I loaded the stock lollipop bootanimation I had been using previously (I do like the omni one a lot, though), and it used to lag a bit at the end on 4.4.4 but now it runs smooth all the way through, so that's encouraging.

-Turning the screen off (or letting it time out) is usually buggy, the screen flickers on/off for a second instead of any type of animation (I believe Lollipop is supposed to do a monochrome fadeout?) Edit: On closer inspection I see it is doing the monochrome fade, but then the screen flashes at the end of the animation.

-Re-installing apps was painfully slow and seemed to hang if I let the screen turn off (I'd find it sitting on the same install several minutes later). Downloading seemed a lot slower than KitKat ever was, too. I looked at the stats in settings->apps->running at on point in the process and the Play Store was listed as Restarting, perhaps this indicates poor memory management? Running the app in the foreground didn't seem to help at all, though.

-The material updates to the stock browser app are pretty swanky, I'm a fan. (I saw that in the gerrit and got excited. Not done yet but looks great.)

-Cast screen doesn't seem functional, doesn't find my chromecast. I've tested both Netflix and Localcast to connect just fine, LocalCast was a bit finicky the first time I tried but I think that may have been a network issue.

-I was testing a video call in in Hangouts and tried to mute the sound (was testing with my phone in hand and there was audio feedback loops because of that), but couldn't. Using the volume buttons, it wouldn't go all the way down, and if I dragged the bar the rest of the way it just wouldn't stick. Not sure exactly which volume control that was (lollipop's sound settings still confuse me in general), but I think it must be a bug of some sort that it wouldn't go down to mute.

-I had only just got around to trying to use my tablet's IR blaster (P5113) for TV control a few days earlier, and I found that the top several smart remote apps in the store don't work at all. Peel actually forces a soft reboot when it gets to the "push this button to test turning the device on" step, consistently. I did get one app working, which only includes remote IR support as a secondary function, TV Guide by Mini Group. Unfortunately the app isn't quite polished enough to be useful to me, but it was notable that it just worked where the others all get nothing. I didn't re-test all of the apps on lollipop but the ones I did(both of the ones linked here and a couple of the others that didn't work) behaved the same way.

-Visual performance generally seems a bit laggy but overall performance is fine (i.e. animations may freeze or lag but the tasks they're covering up don't suffer). Maybe all the animations in lolipop are just a bit rough on older hardware? I find them a bit overdone now that I've played around with things a bit more, personally (not that this reflects on the ROM). I don't really like stuff like shadows bouncing around as I scroll menus, though some of them are a nice subtle touch.

Overall I was happy with KitKat, but I think I'll let lollipop grow on me, these quirks are all minor. Idle battery life seems a bit worse but it's hard to make that call, I've been fiddling with the tablet more than usual to test things anyway.

Edit: Actually after letting it sit overnight unplugged, the idle battery is better than I was ever getting on KitKat. Granted, I made a point of closing all apps before and I think on KitKat I was having issue with casting apps holding wakelocks overnight and that's yet to be tested, but 1% over 12 hours is a pretty damn good baseline. Not sure what caused that wifi drop towards the end, after holding the connection (it gets a good strong signal) for about 11 hours, though.