I'm so glad you mention it! I'm in the process of reading it right now. (Somewhere around 300 pages in; it's a bit heftier than Fire, but so far, well worth the read. I'm thoroughly impressed.)
The first time I read Deepness in the Sky, I felt like the middle was dragging on, because I wanted to get to the end.
Subsequent re-readings have revealed the middle is packed full of content and very good, no filler at all, it can just be a bit much to take in on one shot.
Subsequent re-readings have revealed the middle is packed full of content and very good, no filler at all, it can just be a bit much to take in on one shot.