I find the Harry Potter books about as entertaining as the side of a shampoo bottle, and slightly more poorly written. I couldn't get through the first book for wanting to mark it with a red pen. It is fair to say that I am not a Harry Potter fan. But the Lego Harry Potter games are sublime.
It's tempting to suggest that TT's Lego games are all very similar in construction. But it's really not true. While they are certainly guilty of repeating an awful lot across the various series, each does have its own unique style. The Batman games play more like 2D side-scrollers, the Lord Of The Rings game had RTS elements, the Marvel Heroes edition boasts a wonderful open city, and the Lego Indy games are stupid. The two HP games, Years 1-3 and 4-7, are different still, with their hub area far more vivid and involved than those of the Star Wars games. The hub is Hogwarts itself, and it expands in a sort of metroidvaniaish way as you gain new abilities via the quests.
And Hogwarts is wonderfully realised, far more fun and inventive than the dreary version in the films, and so are the levels. They're both really lovely games, and presumably even lovelier if you could care less about the spods that star in it.