So my first thought on seeing Gai's dad was that it looked like Sage Jiraiya cosplaying Gai.
Kishi's format has gotten stale for me. Besides being locked into a warfare story-telling arc (struggle->failure->insert new character->struggle->victory->enemy gets powerup->startover), I really don't like flashback/character death formula.
Maybe I would feel more sympathy if it wasn't so expected. But this has happened over and over again. And it's a shame that Gai is getting this treatment as he is one of the big characters of the story. It would have been nice to have been weaving his story through the war arc and steadily building to this. Not just boom, flashback, and heeere's Gai!
Anyway, caught the tie in to Naruto with "oldest genin" remark. I can only guess this will come back in the end. Some two fodder nins saying they aren't very good, but that if Naruto can be only a genin and become Hokage then they can too. (That's right, sport, as long as you're a jinchuriki, you can do it too!)
So, there's a pretty big theme of fatherless children in this manga. Both Gai and Kakashi. Neji, Naruto, Kiba, Sasuke. Gaara, for all intents and purposes. (If you know your dad is trying to kill you....then yeah, you get a pass. It's pretty much the same thing.) And now, Ino and Shikamaru.
Only Hinata, Sakura and Nine-Nine.... No wait, Eight-Eight.... No...Ten-Ten! That's right! Forgot her name! Her family is still intact, right? Wait, is she still in this manga?!