already posted this on the battle.net forums
here but I will copy and paste it here
OK so I have been reading a lot of posts on the forums about death knight mobility and such, and I agree with all of it. DK mobility is in a very bad spot right now and needs to be improved in some way, but all of this complaining isn't going to change a thing, so I had some ideas of how wraith walk could be improved.
#1. Remove the cooldown completely. We can't use any other abilities while it is active anyway, and it would still be a strictly worse version of Burst of Speed, but at least it would help us out a little bit.
OR, if we want to stick to the theme of Wraiths, which according to google is:
a ghost or ghost-like image of someone
ghosts can move through things and can't be killed so
#2. Make Wraith Walk let us move through walls and make us immune to damage (before you start screaming OP about the immunity, it would still be strictly worse than the Demon Hunter talent Netherwalk)
(I realise it would probably be too hard to give us the walking through walls thing but at least the immunity? please? you took away our purgatory)
#3. At the VERY LEAST, we should be immune to fall damage during Wraith Walk. As far as I know, other than DKs, every class besides Warlock has some ability or talent to survive fall damage between blinks, slow falls, zen flight, etc.