I read I, Strahd. I was running the Curse of Strahd adventure and wanted more insight into the character of Strahd. With that in mind, I did quite enjoy it. It's fairly simple, and suffers at times from including hamfisted references to explain details of the original adventure. But it's a fun kind of pulpy novel with decent gothic undertones. It's far from the worst D&D novel I've read (than honour has to belong to one of the Greenwood Elminster novels I've read, or maybe to Salvatore's entry into the Sundering series).

I also quite liked that I could give the actual physical novel to my players as a prop, since the Tome of Strahd is an item in the game. And I think two of them actually read it, too.