I wanted to mention the characters a little bit, because their static relationships (for the most part) are simultaneously a highlight and a detriment to the pacing/development as mentioned above. I really have no problem with the main four, other than that Kitahara especially, but also Yoshizawa would obviously be in a "serious relationship" with someone or possibly a couple different guys through the manga's run. For them to be single the entire way through is just silly and unrealistic (not that manga excels in the realism department, but this one in particular seems to be quite a bit more realistic than the average).

Then we have the "new" characters (those introduced after the main four have solidified as a group): Kaminuma, Itsuki, and Tachikawa. Put simply, none of them add anything to the manga. Kaminuma is barely around, and her "relationship" with Itou remains unexplored. Itsuki adds a bit of a "wild card" to the mix with her disregard for personal space, but is mostly relegated to gags and doesn't receive serious examination. And Tachikawa is just shoehorned into the manga fairly late in the run to act as ...sexual harassment for Nishida? Her inclusion doesn't make any sense and adds nothing, as mentioned.

And of course, I couldn't comment on this manga without mentioning the Yoshizawa/Nishida "relationship". There's obvious interest (possibly mutual?) but the mangaka never pulled the trigger. It's definitely not from lack of opportunity; I guess the mangaka just felt that escalating their relationship wasn't in the work's best interest. I think it's the biggest missed opportunity of the manga and one of the main things keeping it at the merely very good level rather than the transcendent work it could easily have been.