Wouldn't complain if I could get Version 4 back. Was WAY more stable than V5.
That's not what I saw when I upgraded? When I went from v4 to v5, I loved the upgrades, and to me it looked much better and felt more stable, although I never had any crashes from v4 either. Unless you mean bugs, in which case v5 is way more fixed than v4, however some bugs can come back after a lot of bugs were fixed, so if you see any bugs/unfinished quests, then that's probably why.
What race/class are you playing, and what problems are you having exactly?
i just downloaded everything. Does Dungeon Finder work? And Battleground and Arena?
I think dungeon finder was disabled for this version, but I never checked when I had v5.