My initial reaction to the Planetes manga was that they ruined Yuri's development. In hindsight, using a few episodes on basically nothing in order to establish the characters was a genius move on Taniguchi's part, because it made the Yuri reveal all the more interesting. That Yuri's "mystery" is solved within the first volume is, honestly, kind of a disappointment. Because Yuri faded into the background after his "arc" in the anime, I don't see how he's going to remain relevant in the manga for 3 more volumes.
Also, Tanabe is nowhere to be found when Hachi's undergoing his the most crucial turning point in his character development.