I have not seen the movie for several years now and it has been even longer since I read the book so I am working with fairly old brain cells here.

In fact I think both were written at the same time and there was some amount of corporation between them. The book of course has more details and it does do a better job explaining why the part with the monkeys and the moon was so important. If you take the monkey and moon part out it is just a movie about. I do think the movie did an overall poor job of explaining the monoliths and what they were doing.

The part I thought was boring was the entire space station and shuttle section. It felt like it took twenty minuets for that stewardess to walk around that tube in velcro shoes.