Honestly, I've played it and thought it was really fun. Just got myself a copy.
From the review:
What do pirates, ninjas, robots, zombies, aliens, wizards, tricksters, and dinosaurs have in common? They’re all trying to take over the world! But they can’t do it alone, so they’re teaming up.
Every combo brings a different experience in this fast-paced shufflebuilding game. Take two 20-card decks, smash them together, and then rock your opponents’ faces!
Each faction has a different style: pirates move cards, zombies come back from the discard pile, dinosaurs are just freaking huge. Each pairing creates different gameplay. And each game is a different throw-down!
Is Smash Up a game you can live without? Not if you’re awesome. Choose a side. Choose two! And start the carnage!