That's actually still on my to-watch list so I can't tell you whether it's any good. Sorry! (I can tell you this tho - for US viewers anyway - it's legally able to be streamed on
www.crunchyroll.com for free)
All I've heard is that it's good, it's about music, and it's a tearjerker. I definitely wanted to watch it but have been busy with other series.
Fanservice is a lot of things. It's all visual and it's all meant to appeal to the fans outside of the story itself. (Rarely it could be just a reference to something old or another series - a callback or something but usually ita gratitous content....) It could be as mild as really short school skirts or guys who have a tendency to go shirtless. The stuff I have watched will go as far as mostly undetailed nudity, up-skirt shots, bathing scenes, extremely revealing costumes, etc. I'm also aware of the big culprits when it comes to fanservice that I haven't watched so I can recommend what series aren't worth trying.
(This is why I said don't google it because you're gonna find all sorts of icky stuff on google)
Not to be confused with fan disservice which is elements that ordinarily might be used for fanservice but end up coming off really horrific. (For example nudity during an autopsy is fan disservice)