Has anyone tried these books? I just picked one up but have never heard anything about them.

I liked the first two a lot -- found them very funny. It helps to have read some of the Jeeves and Wooster books by Wodehouse before you read the Mortdecai books, as they're something of a parody of Wodehouse, but it's not required. The third Mortdecai book, though, is pretty awful. Rape just doesn't make for good comedy material, in my humble opinion.