Also, he spent way too much time (in my opinion) on irrelivant stuff. Fredo did too much stuff that really accomplished nothing in the storyline but rehash the point that he was a bumb with a crazy idea to move a ton of corpses. Also, to touch once again on the lack of linkage with old characters, he basically created several new people and gave a little more substance to characters that were there just for completeness.
In short, it doesn't interfere (very much) withu the movies, but the linkage isn't that good either.