For instance I loved the Miki/Sakura romance subplot and the Nagisa VS Sakura fight. But I cant help but feel that the VN would have been much more awesome if one of the "six friends" (or even Reji) actually was Odin. As Odin was now, it feels like they wanted to make a sequel, but then found that they couldn't. Cue massive coveruping to tie up all the loose ends.
Maybe it was me, but I was pretty sure that the prologue referred to Reji and Sakura (instead of Odin and the other one), since I think it even referred to "two souls in one" and it was Rejis VA speaking in that scene.
Dont get me wrong, I loved Fortissimo, but I cant help but feel that a great opportunity was missed here.