I love my Tomb Kings they are however quite frustrating to Keep the momentum moving due to being unable to march and not being able to increase unit size (unlike Vampire Counts). On the plus side there is a variety of builds that are viable so should keep you occupied for a while. Personally if you want a TK army take the plunge they are easy to play but hard to master which is what I love about them (that and I never really like Vampires, Bats and Wolves as undead)