I 100% agree on both positive and negative points. I see a lot of people saying that it's too difficult, but yes, it does get easy after a while of practice.
I want to point out that
1: I experienced trouble with pressing buttons on VS. Synthz McWave in addition to the two that you mentioned, so it might just be a bug on all the maps.
2: I S-ranked all maps on keyboard, so I think the part about needing a controller might just depend on personal preferences.
But yeah, this game SLAPS. Love this type of rhythm games.