Zach didn't say the book is too long. If you've never read '20,000 Leagues Under the Sea', or any other Verne novels, it is a little difficult to explain. (Highly recommend the Puffin Classics version of all of his)
The thing is. If the description fits where it goes and does something for the overall atmosphere, or progress of the story, then that is good. For instance Lord of the Rings is full of description, yet it all falls into place and adds atmosphere. On the other hand, if he had launched into a ten page description of the shades of dark in Moria. Then I would suggest this would be over the top.