This game was a really beautifully designed game. I loved how it looked, the only thing I'd have maybe changed was a bit more fluid wall slide and jump animations. I also feel like the spikes were too similar to the ground colour so sometimes I didn't even see them.
I think, as others have mentioned, the difficulty is really high at the beginning. Would have loved it to be slightly simpler to begin with and then ramp up in difficulty. There was also a couple of parts that didn't flow so well in terms of aiming a wall jump and getting stuck on a wall instead of going through the gap. In instances like that the gap should have been lower.
Nice game though and I enjoyed playing it.