Despite all the massive negative feedback on forums, there are things that Legion actually fixed.
1. Faction balance.
If you look at all the ladders today, you'll see a 49-51% ratio. Compare it to end of MoP and WoD with 96-4% (total Alliance domination).
2. Human racial + problematic trinket procs
Race is no longer a big deal, since proc trinkets are disabled in instanced PvP now.
3. PvP entry level
Any casual can get into PvP much easier now after just dinging 110. Thanks to templates, the margin between high and low ilvl is not that high as it was with greens / PvP gear in previous expansions. Also, you can get plenty of 840+ drops very quickly.
4. About class imbalance
YES, of course, there are class imbalances. But it's been always this way, since the first patch of WoW. Name one season where some class / spec wasn't imbalanced.
Then, look at the ladders here: http://www.arenamate.net/
Look at spec percentage. Going slowly down from 7.7 to 3.2, but without drastic jumps. Compare it to WoD with Arms Warrior 12-15% and Frost Mage 9-11% up with healers, and then all others MILES down.
Actually, the current curve is a lot more balanced than in WoD. At least it's what statistics say.
Yes, PvP has its problems, but I think that many of the complaints aren't justified.
P.S. Yes I'm aware of 40% less participants in ladders. However, it's more on low end than on high end (look at glad range and you'll see same eternal Walliriks and Minpojkes and so on). Cause explain to 1200-1500 people why bother with lot harder and longer (healer dps vs healer dps in 2s come to mind) rated Arenas if you can get gear / prestige easier and LOT FASTER from random BGs / skirms / WQ? Here is the answer.