...Well it's definitely no Cave Story. Not really similar except in a very general graphical/music sense. Once I got past my disappointment of the type of game it was (more of a portal / action puzzle platformer 2d game), it ended up being quite fun learning the mechanic of portal jumping, finding secrets and 107%ing it (says I played 5 hours, but a good part of that time was doing things I wasn't supposed to do, like make it outside of some areas you aren't supposed to go (not that it really did anything), and attempting to beat a certain "boss"...
You get about a hour of gameplay, more or less depending on your ability and if you want to find everything.
Great deal for the price :]