I love it (more than 20 hours in). And I hardly ever play on-line (and when I do, I always feel I ought to apologize to the other players about how bad I am relative to them).
It’s very hard in a good way and an absolute blast to play locally. Genius co-op action. And we love collecting all the Arms. This has replaced our weekly MK8 fix.
Im addicted to it. Play anywhere from 3 to 25 ranked matches a day. The more you play and better you get; the competition gets heated and rewarding. Did not expect to like it so much. Cannot be a casual player though... or you'll be stuck at 7 Rank and get bored most likely.