I just cannot see the hype about this one.
Generally, I consider a good screen love story if you can "fall in love" alongside the characters, understand their mutual need, getting caught on in their chemistry, affinity of minds or soul. It goes for any relationship really: friendships, family...
Here you can feel it as they play together, just the 2 of them before fixing the vacuum cleaner - but that's about it. There's no "spiritual"/mental one as a Before Sunrise, no "first love" as a Normal People, no escape from loneliness as in Brokeback Mountain, no prolonged musical affinity as a Begin Again or even A star is born, no "finding each other in a dull world" as in Carol... I could have seen it in exactly the same way, without the romantic part. Just as two strangers finding themselves through the creation of an album. Or, even more shockingly, without any kind of relationship involved: just the struggle of a musician to get on with his music and his life.
No nuances, no shades.
I feel most of the positive reviews are affected by getting emotionally carried away with the music part and the camera in hand style: but if you look beyond - to writing, silences, intimacy, acting... even to the simple feelings from the relationship and not the songs, it's quite disappointing.
Totally different movie, but I got the same lack of emotion in The Spectacular Now, as a comparison (even by loving Woodley and Teller's portrayal and skills)