Pretty much what @Frelude already said: Isometric isn't a good fit for a platformer, and because of that (and ledge that shouldn't stop you if you're in the air, but they did anyway) every jump was hard, even the easier ones. I also struggled with grasping the directional controls.
Other than that, this is a good take on the theme, and the game was (excluding all the struggle i had) pretty fun!!
PS. Simon may be a dick now, but in the end it's just a misunderstood guy. Try to show him some love, and know him a bit, and i'm sure it'll open up... Eventually :P