I've now played Warhammer for about 50 hours, long enough to have a pretty good impression of the game. My Warrior Priest is now rank 25, or about halfway to the max level of 40. I've done a fair amount of questing and open RvR combat, but few scenarios and almost no instances. I haven't seen the endgame at all. Anyway, I've played enough to have some opinions on what works and what doesn't.
- Open RvR. New players can jump into PvP combat at rank 1 and level up exclusively fighting other people. Or you can casually jump in and out of RvR regularly when you want a break from questing. There's a series of easy to understand RvR objectives, clear rewards for winning, and a chance for victories to have some lasting effect in the world. When RvR goes well it's really fun.
- Tier structure. Levelling up is broken into four tiers, one every ten levels. PvP is grouped by tier but normalized: low levels are boosted up enough to be able to fight reasonably. It's easy to wander all over your given tier without getting yourself into trouble, the progression is more free-form than WoW's equivalent of 20 or so tiers. For variety there's three zones at each tier that you can hop between.
- Graphic models. The armor and weapon models are beautiful. Simple, themed, and distinctive. Every class looks quite different because of their unique gear. Everyone knows what the bald guy with the big hammer is gonna do as distinct from the skinny elf girl in a bikini with sharp knives. And armor dye makes it easy to customize your look. The world and NPC models are a bit ugly, but the character models make for great dress up dolls.
- Class balance. The game feels quite unbalanced now, particularly in PvP combat, and a major class balance patch is looking. AoE damage is way overpowered. Crowd control is also very annoying in PvP; it's never fun to not be able to move.
- Social environment. Open RvR is mostly a pick-up group affar, randomly joining up with whoever else happens to be playing. There's always some complainer who whines that his side sucks, or everyone is dumb, or the healer isn't healing him. Good leadership in RvR is very rare.
- Public quests. PQs are a really neat innovation in Warhammer but in practice they don't work. The problem is no one else is ever doing them. And the PQ content itself is a repetitive grind and the more grind-oriented players would rather spend the time PvPing for the greater rewards.
- Code bugs. There's a lot of silly bugs in Warhammer, like tooltips showing the wrong info or NPCs that are stuck on the border of two zones or dead spots in the UI. There's also deeper design problems: a lot of visible lag in combat, mail and auction servers that are so overloaded as to not work, etc. A lot of the gameplay feels like fighting the software.
- Endgame? I haven't reached the endgame yet, but a lot of players complain it's not very interesting. Not much PvE content and a repetitive RvR game that gets old.
Warhammer is the one game to come along in the US that's a significant challenger to Warcraft. Blizzard responded strongly, making sure its players stayed interested in Warcraft. But I think no matter what Blizzard did Warhammer would be in the state it's in now, a good game that's not the huge success they were hoping for (from 800,000 subscribers at launch to 300,000 now).