All core parts of the game work well. The controls are a little slower than I'd like, but I got used to them quickly. I like the wall-climbing; for me it's a preferable approach than wall-jumping, and it opens a lot of opportunities for exploration.
Even the basic enemies are surprisingly strong--an enemy this early in the game should not take more than 2-3 hits to defeat. Also, they should at least occasionally drop a healing item when defeated.
Note that I ran out of health, but never died. Either the fail state is not implemented, or it's not working consistently.