After playing for 9 months....
I remember when I finally hit 40 (a month or so in) and my roommate who was not very familiar with MMOs asked what I do now that i am max level. I replied by saying that now is when the true game begins. At the time I said that in an excited tone, but if only I knew what I know now, I would not of been. To begin, the game its self is not well constructed in regard to coding. RvR (realm vs. realm) in t4 can get very large with hundreds and hundreds of people fighting in one zone. There is generally a lot of instability in situations like this. This can be expected in any MMO with so many people. But there are so many glitches (abilities not working, enemies disappearing) and so much lag that it can be a lot of times unplayable. I will say tho that Mythic has made great improvements in this aspect of the game since the first 6 months of the game or so.
Monstrous lag is not really that common though, so it can be overlooked most of the time. Unfortunately, the biggest problem with this game is its end-game content. The PvE in this game is generally terrible. Mostly all of the PvE (except the new Vulture Lord instance in the expansion) lacks any depth what so ever. The sad thing about that is the PvE is the only way to get the best gear. Mythic has tried to make PvP a more viable option for gearing up, but it is still not so. This is why I believe so many people left this game; this is a PvP game but the best way to gear up is the crappy PvE. (on a side note, I say the PvE is crappy, because the bosses really do nothing cool like bosses in wow and are mostly just a gear check)
An interesting aspect to War is its classes. There is a diverse amount of them on both sides all with a wide range of abilities (even though the two factions for the most part, have mirrors of each other). With the dye system in the game and the class diversity, you felt really unique with what ever character you chose and how you wanted to customize him. Unfortunately the class balance is not a strong suit in this game. Certain classes are noticeable the best classes to play while others are noticeable underpowered. Mythic is tirelessly trying to correct this, but they still have not succeeded. Along the same lines of the different classes is the combat itself. Early in the game the fighting is very entertaining, but later in the game there is just so many Crowd Control abilities (stuns, knockdowns...) and cheap stratigities that combat, many times, becomes very unsatisfying.
The reason i mostly left after about 9 months is because nothing in the game really had any meaning anymore. I killed Destruction's king (The final endgame boss), Open RvR became nothing more than a boring task of gathering more numbers than the other side, and most of the cool people I met in game left. The only thing I had were scenarios (instanced 2-5 group pvp games) and they were no longer a challenge because mostly all the good hardcore players left.
All and All, Warhammer has many good elements with in this game. They have a fun class system, and interesting PvP driven progression, and a highly detailed world. Unfortunately by the time a player reaches end-game content, they will find too many things that mar the vision that would be a truly quality MMO. For all those interested in trying out Warhammer, I will not stop you, but know that this game's prime has past. You will have fun facing other players in battle every time you log on, but I feel that the game's lack of depth will fairly quickly rear its head. I played for about 9 months... I don't regret it, but I still feel a little disappointed when I thing about it