As far as I can see the level is perfect, except for one thing, at 1:32 into the video sonic starts running through a hallway, and every time sonic runs on one of the cracks a huge piece of rock rises up fast from the ground to crush sonic into the roof, but I don't think the rock pillars rise fast enough, because from looking at the video, if you just hold the run button, you can practically get through the whole thing without even knowing that anything's happening, which wastes a good gimmick.
If you make the pillars rise faster, you'll notice that sonic's constantly being raised by pillars to the roof, players will notice it as another good feature of the level and it'll give a sense of panic and difficulty rather then just being able to run through the hallway without basically seeing the pillars rise at all, which is all I can see in the video.