I picked up Roundabout last night, I'm not sure what I think about it yet. It doesn't seem to know what it is - the ambience says "wacky throwback action", but the gameplay requires precision and patience. You have to time your moves exactly with the rotation to get through narrow corridors, etc. You rarely get to move at anything resembling speed.
Going along with that conflict, the game has ~12 goals for each mission ("Finish in 12 seconds", "Collect all coins", "Take no damage", etc) but it plays the exact same voiceover/cutscenes EVERY SINGLE TIME you restart the mission to get a better time or avoid damage (and every mission seems to have unique cutscenes/voiceover throughout). So if you're working out how to get through a tricky part without damage, it becomes an infuriating experience. This resulted in me turning voices off completely after about 30 minutes. A Score Attack-style mode shouldn't have that shit repeating endlessly.
I'd give it about a 5/10 after an hour or so, that may go up or down depending on how the rest plays out.