I played through Dawnguard as a hunter, now I am playing through as a vampire on my main character. I love the idea of being able to morph into a vampire lord and wreak havoc, but this form is becoming somewhat unplayable.
I understand (even if disagree with) not being able to interact with anything in the world except doors, and the fact that i cannot fit through all corridors. That would be fine considering I can switch between forms at will.

However, here I have problems. When I hit Z to transform, there is often a lag of up to 10 seconds or more before the transformation even begins. Then once the animation has taken place, I am often unable to attack for a while and I have to try and fiddle with swapping between magic and melee mode, opening favourites menu, etc, to try and get my vampire to work. All while being attacked, or while my companion steals all of my kills. Then when I want to transform back, there is another delay after i hit z, my vampire lord shimmers, then lo and behold, I am still a vampire lord and I have to just wait (sometimes up to 30 seconds, even over a minute) for my character to pop back to nord-form. Sometimes hitting tab makes this change work.

Having to go through this process every time (and last time I couldn't even transform back, had to reload a save game) makes it very frustrating to play. Is this common, or is something messing up?

Cheers,
Kashaaz

I'm having the transformation delay as well, haven't noticed inability to attack though but that might be because I don't even bother to transform anymore as it's way too annoying.