On design: Mal.
Screens did not have a coherent style. It seems the designer just threw in tilesets which he or she felt that were nice because he could due to the plot device of the coma.
Those horrible plasticky yellow walls could go. The white screens (with the blue boxes that turn invisible) don't look clinical, but scruffy.
Design could be improved by using a common style in tilesets, and using tilesets which compliment each other aesthetically.
No objects were used.
I doubt if layers 0, 1 and 2 were used in more than three or four screens.
Sound (original sound isn't necessary in my opinion) was normal (?).
On gameplay: Ok.
However the level was short and most of it involved climbing up a wall and going back down so you can warp to a new screen. If I were snidily sniping I would say that perhaps its shortness saved it from becoming tiresome. However I don't think that is the case, it is more the fact that the level is so easily playable and one progresses fast. The technique of warping and abrupt tileset changing probably helped in creating this notion of a great distance covered in short time.
On plot: Ok.
The intro was unnecessarily long. Interesting and compelling writing (of which we see little in video gaming) was there, it's just that it wasn't needed to that extent. You could utilise it in a better way if you somehow wrote the plot as the level went along, still of that high calibre, instead of loading all at the intro. That resulted in pretty much leaving the rest of the level detached from the continuation of the plot as it's pretty much written beforehand.
In a nutshell:
Worst thing: Your screens were empty.
Best thing: The level succeeded in being easy and light.