Is this game worth about $30?  Gamestop has it on sale for $40, and once I beat it, it'll probably be worth $10 or so trade in.  
 
Is it worth it to go get this game and play through it, or am I going to be disappointed and frustrated?

i thought it was really fun. see if you can get a bud to split screen it with you. its pretty short though. like 6 hours maybe.

Meh, it's probably worth $20.

nope

I was very disappointed with the demo, so I wouldn't even bother.

My friend picked this up because he needed something to play.
It's since become a running joke.
 
He's coming up to stop at mine for a few days, and he keeps telling me he's gonna bring that, hide it in my room then tell me where it is when he leaves. 
So I have to have the burden of having it in my game collection like he has since it's release.
 
Based on that, I'd say no, nothing else you can get for $30?
Or maybe save it for another game in the future.