If you love live music and playing in a band like me, this show is a fairly fun and ultimately inoffensive show. It's not going to amaze you in any singular aspect, in fact the anime sort of just felt like a love letter to independent music venues, that unfortunately are slowly dying out.
I was however pleasantly surprised there was depths to the anime beyond the show just being another cookie cutter 'Cute Girls Doing Cute Things' series, such as character motivations beyond just the surface level - people are complicated, and by extension so are bands, so it's good it captured some of that reality.
In the end though, a music anime relies on the actual quality of the music to be successful and this show has no spectacular songs at all to be totally honest. They're passable for the context of the show, but I'm not tempted to go back and listen to them again. It's funny how the characters don't even consider getting a drummer until the opportunity literally falls onto their laps though. Also, the show liked to focus on the girls posteriors quite frequently which was sort of strange for an otherwise completely clean show, but hey that's Japan I guess.
But my biggest gripe with the show is the way everyone is a bit too... nice. It's as though there's no spiteful bands, no arrogance or anything of the sort. From my own experience there's plenty of arrogance surrounding bands, especially when you're sharing the stage with another band. Also, when the band plays it doesn't sound live, especially the vocals.
If you haven't seen either 'K-On!' or 'Beck', watch those before hand because they are infinitely better. This show is ultimately trying to capture the atmosphere of 'K-On!' but handles it haphazardly when compared to a masterpiece like 'K-On!', which actually gives the band a measure of authenticity in the way they improve as a band, and the way the sound design matches that of a live concert when they play in their school hall, or sounds like they're playing in a smaller room when they're playing in their club room. Both the main character in 'BanG Dream!' and 'K-On' share a similar childish demeanour, both have little sisters, both play guitar and sing. But if you were to choose a better and more believable character, it's not even a contest.