Some info on the issues http://m.bbc.co.uk/news/technology-30116319
Checked my Nexus 7 out a bit more thoroughly now it has lollipop on it.
I found a few issues:-
1) AceStream engine doesn't work. (There is a fix though by googling "[FIX] [Android 'L'] Bypassing the new PIE security check")
2) Bloomberg TV doesn't work.
3) Sky Go doesn't work. (Sky Go always stops working after every Android update, so nothing new there. Eventually Sky will sort it and upgrade their app.).
4) MX player app had to update to get it to work with lollipop.
5) GPlayer had to re-enable software decoder as lollipop managed to switch that off.
Not the best Android update it seems, but app developers will undoubtedly update their apps for lollipop (those that haven't already).