I have been playing this game with my friends. Very very fun. It really puts me into the zone and keeps me there for a really long time. 

That said, there are some things that are confusing. Mostly the progression system for me. I don't understand how resources get added to the tree and when playing with friends, it seems the host has to unlock everything or the progression won't be shared. At least that is how it worked for us.

That is just a minor issue though because we just play and when I can unlock stuff, I just do. Fun game, and worth a try.