Most of them look great.
We already are going to be able to get characters, other costumes and colors by playing, but I'd love to get these costumes too.
But well, it's the price of not having to pay $60/$40 for a revision with gameplay tweaks, rebalances, new characters and a few modes, because we'll get this for free and without splitting the userbase.
I'd have started with more singleplayer content like the March update + arcade mode, but other than that it's a great model for me.
Can't wait to see more content like new stages, and let's hope they make a second season pass for premium content (stages + costumes).