I played through Akira's route (because she's best girl) and, honestly, that's all I felt like I needed to play. Basically every major question about what's going on is answered by playing this single route. I can't say for sure if that's true of every route, but it seems likely based on what I saw skipping through the others. I did read a decent chunk of Natsume's route as well since she was the biggest mystery remaining after Akira's, but other than finding out what her personal deal is, there wasn't anything new.

I prefer games that have drastically different routes or ones that encourage you to play them all to piece together the overall story bit by bit. This felt like it was just "pick your favorite girl (or Makoto) and find out everything." This would be fine if the romance aspect was more fleshed out, but it kind of takes a backseat to all the sci-fi stuff going on. Oh yeah, I forgot to mention you're running around fighting monsters using some virtual idol group's songs for half of the game.There' s a virus going around that infects only women for some reason I didn't catch or wasn't explained. It causes some weird looking rash and eventually turns them into monsters who go around attacking people. You find out Kanon is the queen and you have to cure or kill her depending on the route.

The rhythm game mechanics are pretty meh. Each member of D4U uses one of the buttons and you just have to hit it in time. It's pretty forgiving, but you don't even have to engage with this mechanic. You can skip every battle in the game except the tutorial and you can even put that on auto.

The trophies in this game are also glitchy. I used skip to clear every single end and get the CG, but a couple of the ending trophies never popped. There's also a trophy for getting 100% on the chart which is VERY tedious.

TL;DR - If you're going to play this, I'd suggest picking a girl and using a guide to just do that one route. It's not good enough to warrant doing all routes.