However, I did have a bit of difficulty with the wall-jumping. I couldn't seem to use it reliably enough to escape the monster's clutches!
Yeah wall jumping is a little difficult. It doesn't feel natural having to press up and jump again after pulling off one walljump, well not to me anyway. Maybe have it so you can hold up and press the jump button as many times as you need to perform wall jumps.
Checkpoints - I didn't get very far but are there any?
The Monster cheats! He's fairly quick and can move through the walls and when I have to wall jump I sometimes get killed by him because I have to jump towards him.
Keep it up though