What makes Love Live great is not the story. What makes it great are the sound, colors, characters and such.
I'm going to assume you've already watched the first season.
The story is fair(6/10), Why? Because it's not like the main cast are idols for no reason, and they have a goal in sight which they work towards it.
Why didn't I like it? It's the same story as Love Live School Idol Project-
School is closing down, a second year girl opens a 9 girls idols group, 3rd years are leaving soon- DRAMA. I don't have a problem with the fact the leader is a 2nd year in both anime, and that the group is 9 girls, but all the rest of the story... Please no.
And also let's not forget to include an evil 3rd year (who's also a student council president!) then make her join the group and see she's really sweet.
I can rate Art/Sound 10/10. The CGI in general of the dances, the songs themselves, the OP, the ED, (and kinda the soundtrack), all of it are amazing. That's the very reason I am watching Love Live.
While I think it's too sad the anime is taking the same "drama" route (at first it is more comedy based- which is much better), but ignore that and you have a really sweet anime.
The last parameter that I want to talk about is the characters, which I gave 9/10. Why is that?
We have a pretty different cast, where each girl is different from another. I DO think though that many of the personalities are µ's recycled, but not fully. As well as I can say most of the girls are likable (or more. Have fun with your waifus).
Overall I am enjoying the series so far. It won't be my AOTS(Anime of the season), but definitely a fun watch. 9/10 overall. (At least for now)