Bill King is a very talented writer. I really enjoyed all the 7 books that he wrote about Gotrek and Felix. I think he fleshed the heroes out very well and we really get a nice feel for them. I love the comical moments as well - the humour is very good.
I think that Grey Seer Tanquol is also priceless in here, and it's no surprise that the Grey Seer is one of the most popular Black Library Fantasy characters - he is funny, he is evil, he is exceptionally cunning, and he is often unlucky.
I think that indeed the very first book was a bit raw, but nevertheless it was still very good. Out of the 7 books, the one that I enjoyed the least was the Vampireslayer (I am just not a fan of Vampires), but I would still say that the whole series is simply amazing. My favorite book was the Skavenslayer. I can't wait for Bill King to return to the Black Library and start releasing great Warhammer books once again.