I want to stress that my opinions were formed by my experiences mostly on Phoenix Throne but also Iron Rock. I can't speak for the other servers.
Let's start off with my likes. I really get the sense that the WAR developers have their nose to the grindstone right now. At launch and throughout beta, Mythic was taking a smaller but more frequent approach to patching the game. For a while there, they moved to larger and less frequent patches, which I wasn't a fan of. It seems that recently they've moved back to their original approach, which I think everyone appreciates.
Despite all the forum hate WAR seems to attract, the game doesn't feel dead. I'll grant you that servers have been merging like crazy over the last six months, but being on a server with a healthy population is quite busy (in terms of RvR anyway -- more on that later). The monthly Live Events do a good job of introducing fresh, if not temporary, content to the game, so that keeps things interesting as well. It seems WAR is at its busiest during Live Event weeks.
Mythic seems to have grasped that RvR is the bread and butter for their game and has really spent the last year refining it. City sieges have been improved. Keeps are more dynamic. Even fortresses are going to be reworked soon. They've added tokens to buy RvR set gear and made it so that players randomly drop certain set pieces too. You can now find all kinds of fights from small to large scale (1v1, group vs. group, warband vs. warband, etc.). There almost always seems to be some kind of RvR going on and at its best it can feel frantic and fun.
Community. The community in WAR is great. I say "in" because I mean the players, not the ex-subscribers who seem to gain pleasure from prophesying imminent implosion. I really feel like the remaining players are satisfied with the game because they've stuck around with it though thick and thin. Players seem to be much more friendly and accommodating than I remember.
Finally, Mythic has made vast improvements in terms of game performance, bug fixes, and polish. Population balance doesn't seem completely out of whack and neither does class balance, though they're still making improvements in these areas. If the game launched in the state it is in today, I think WAR would have held on to a lot more subscribers than it did.