I'm not really a fan of the Mario Party series, and Super Mario Party isn't an exception. In a group setting of four friends looking for a way to burn an hour or two it's acceptable. The minigames are generally fun and well designed.
At the core, Mario Party games are intended to be casual no-pressure experiences, where you just goof off and have fun with friends. However, the game still provides a win condition, and therefore pressure to compete. Getting good at the minigames gives you a quick advantage against more casual players. But the game then constantly subverts itself with random prizes of coins, stars, and items... and an ending sequence where three additional stars are handed out based on random statistics.
It's a competitive game where being a competitive player is subverted by random chance. For me, as a player, this gives me a bad experience. As a casual player, I spend an hour or two constantly being crushed in minigames by "better players", and I can still walk away "with the win" because "good" players can have all their efforts blown away by a few random rolls of the dice.
But hey, the rest of my friends love it, so maybe that's just me.