These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Esoteric Happy Ending: Suzuka reveals that she's pregnant with Yamato's child. They decide to keep the baby and both of them table their promising careers as star athletes while Yamato's track rival as well as his underclassman become representatives of the Japan Olympic track team. Although the story points out that Yamato and Suzuka get married and were happy facing a new future as long as they were together, many readers feel that it was an unhappy ending since they had to give up their dreams.
The 4komas point out it's far from an unhappy ending.
Although the events of chapter 36 in Fuuka render a very, very bitter aftertaste to the ending with the death of their daughter.
Idiot Plot: Yamato says something that damages his current relationship, then does exactly the wrong thing to repair it. We have just described every chapter after about Chapter 5.
What an Idiot: seriously, 75% of the lines coming out of Yamato's mouth qualify for this.
Yamato gets somewhat less idiotic and more clued in to Suzuka's moods as time goes on, particularly in the latter half of the manga. It doesn't save them many arguments, though, because she really is a major Tsundere. (That, and the mangaka seems to specialize in problems created by misunderstanding and perpetuated by one or the other party's pride keeping them from talking for a chapter or two.)