Unless the Nagash book is the way things are going to be once 9th Ed rolls around, I wouldn't put to much stock into the funky rules in there. From what I can tell it's just another supplement like Storm of Magic was. I would concentrate on the rules in the BRB and whichever army book you choose to use.
I play VC as one of my armies and, while not hard to play, the strategies vary quite a bit due to the different ways in which they calculate combat, how much they rely on magic to keep the army moving/replenished (more so the latter), how horrid their Core choices are in combat (worse than Gobbos!), etc. So, like TK, easy to play if you know the basic rules, a little different to master. However, if you're not starting a new army after having played a "normal" race, it may not make to much of a difference as you'll have nothing to compare it to.
