I like the premise and the design, but there are some issues around the controls, even setting aside the part where you walk forward towards a vertical surface and you rotate 90 degrees as if you're trying to walk straight up it.
I ended up getting stuck in the mushroom's cave, when I went off the right side of the tall block (towards the roots) and couldn't get back out. Even before that: I jumped onto the ledge before the pollen-spewing thing (the one in the first screenshot), and then died during the dialogue. So that wasn't great....