I recently tried WAR again, and it just doesn't feel natural.
I'm pretty sure it's the engine, but here are a few things that bother me.

Mounting - It just feels weird, I can't put my finger on it, but it just doesn't feel like a mount. It feels like I got a speed buff with a weird animation.

The quality of the game - Whenever I'm running and see another player, specifically the opposite faction; it looks like they are either lagging or the game is having trouble rendering their movement.
They don't look like they are running naturally, more like you are seeing things at two frames a second. It's hard to describe without seeing it.

Server to Client lag - I still see Ability and Item lag, such as moving stuff around in my inventory or using an ability when I want it to. It gets very annoying on a positional DPS class.

DoTs - DoTs just don't feel very fun, you know how in other games when you DoT something so much you laugh and feel evil knowing they are going to die? You don't feel that in Warhammer - you feel like you better keep reapplying the DoT five times over to make sure they die.

I probably have more but I can't think of them at the time.