This. I effectively paid less than $0.50 for my copy (trading FTW), and I got TONS more value and playtime from Terraria; in fact it's my third most played game on Steam, at 133.9 hours played. What do you expect from a $9.99 price game?
Anyway, I'm pretty hyped. I just finished watching the trailer that the OP linked, and that was the first I had seen of the game. I'm having high hopes, and it'll likely be a Day 1 purchase from me. Can't wait!