I played it a few times back when I thought it would be a decent way to nab customs, but it's incredibly chaotic and I feel myself getting salty when I shouldn't be. I get a character I like, only to have them stolen from me because someone else spawned with a hammer, and now I'm going into the final fight with maybe 3 characters I'm not even 10% proficient with because they were the only ones I could pick up. It might be fun with a bunch of friends that aren't too serious about the game, or younger children.
But that's how the game is played and meant to be. Chaotic and crazy. I don't really like it much, myself. I don't think I'll ever be able to complete the "recover the stat boosts a Metroid stole from you" challenge because of my distaste for it. I'd have preferred Smash Run 2.0 or the old Classic mode, but it's water under the bridge now. Hopefully the team learns from this and decides on a different mini-game next time.