Miitopia is extremely repetitive. The same enemies and events are constantly reused and there is virtually no variety in the combat.

The biggest thing it's always had going for it is that you can use the built in Mii editor to create virtually any character you can think of. That, in itself, is a very big plus, but the rest of the game is uninteresting and requires little to no interaction with the game aside from the maintenance you'll do in between levels (even that is pretty straightforward).
I'd say playing through the first four areas is a bit of a fun time, but anything past that is extremely barebones.