While the game made a very silly and kiddish first impression, the more I see of ARMS the more I like! It looks like the game has a lot more depth than what we saw in the initial reveal, and the more people I hear about playing it, the more excited I get. It sounds like this game could be celebrating some Splatoon levels of success on its release!
If you're doubtful, take a look at this in-depth gameplay from the Nintendo Treehouse stream that outlines the customization system, different playstyles and strategies one can implement against foes. I think you'll agree it's surprisingly deeper than you initially thought.