[martin82]

I don't agree at all.

VERY few authors write consistenly good books.

If you liked one book by an author, it is not at all likely that you will like the other books as well. For example, Neil Stephenson is probably my favorite author alive today, but I hate almost half of his books.

The only author that I can think of where I read and liked every single book was Terry Pratchett, and that might have be a case of "I was still young and easy to impress".

[blehn]

I didn't say it was likely that you'd enjoy the other books by that author. My point is that it's not helpful for a recommendation system to recommend more books by that author — it's common sense. If I've read a book by an author, it's easy enough to look up their other work and decide whether I want to read more of them.