I've read a few, none are literary classics.
The Drew Karpyshyn Mass Effect books are pretty good, I hear the one that he didn't write is a total mess though, much like the end of ME3.
I enjoyed most of the Halo books but refuse to read the newer ones because I won't read anything by Karen Traviss after her Star Wars madness.
Read the Resident Evil books many, many years ago. They were elegant books for a more civilised time. Well they were alright, brilliant if you think Rebecca Chambers is the best person in the history of the world and can do absolutely anything. They also try to explain why Jill is the "master of unlocking", a mystery that really didn't need solved. She simply is, because Barry said so.
Tried reading one of the Gears of War novels, it was s**t and I couldn't finish it.
Thats all I can remember off the top of my head for novels based on games. I got a coupe of Eldar Scrolls ones for free but have never gotten around to reading them.
Going in the other direction, The Witcher books are excellent. Two are available in English, with the others still being translated, it's taken years. But they are available as free fan translations for Kindle, pretty good translations from what I've read so far. I'll get you the link if you want it.