The Specialist round themes are quite wide and varied and there is nothing "too" narrow where you will be tempted to skip it. I think the most narrow it gets is either "Star Wars movies" or "Hitchikers Guide to the Galaxy". the first few I tried were the Summer Olympics, Academy Awards and French Revolution and they were all enjoyable.
I am also pleased to see in the GK sets that they don't seem to have too many "gimmies" in there that you see on the show so the book is not filled with simple chestnuts but instead the more advanced questions from the GK rounds on the series over the years!
Factor in at the end of every couple of "shows" you get interviews, titbits and features on all things Mastermind, you have a very top quality quiz book here and one I would strongly recommend.