Game is solid but a bit overrated. I didn't knew much about this game other than the fact it hit Steam some years ago - Experience was so shallow I didn't even remember it until now. Playing the demo through gave me what I needed to rate this game 4 stars: Everything is nice, but gameplay gets quickly repetitive and the "macabre" atmosphere fails to amaze me due to cartoonish style (Well, it may be me who is used for more terrifying games, but still).
So, in short: Good game, but it does get boring quickly. I know this is a demo, but it got boring by level 2.
If the full game really has more to it (I mean more FEATURES and not just more levels) then it's definitely worth the $5 price. If not, then no - I wouldn't pay just to play more of the same.
Also, I played a lot of entertaining games with tons of content for free (both flash and Steam) so it's hard for me to recommend it.