Enjoying it maybe more than I expected. Making levels is fun, even if I don't expect many people to play them. It's interesting to see so many people share designs - I wish they at least QR coded level sharing. Facing the gampad at a monitor would be dumb but it'd speed it up.
Playing Normal 100-Mario challenge can kick in some fatigue (hopefully levels get ironed out). I assume a lot of it is people bombarding with loads of levels/not having everything unlocked. Hopefully they get some Miiverse level of curation going on.
Every time I feel a bit fed up, I'll put it down and come back to it and be surprised. I've even started to enjoy some New Super Mario Bros levels after playing through the NWC levels.
Bit surprised there isn't any form of ranking/leaderboards on levels. It'd give me some incentive to play through those terrible levels that can appear.