Mario U is a consistently satisfying throwback to 3 and World. It’s use of older ideas (often lifted directly) can be shallow but there were still enough new elements to keep me engaged. The challenge was compelling enough that I was down to my last life and resorted to the easy crutch of the P-suit on the final encounter.
I didn’t feel the need to go back for secrets immediately, but will likely return to it in the future. Unlocking the secret areas requires finding every star coin in a world, which is a bit more work than I feel like putting in when there are other games to get to. Hopefully it’ll be a great little diversion one day.
If you hated the Wii version of New Super Mario but loved older 3 and World, I highly recommend you give this one a shot.