Gave it a run through this morning because I didn't have the chance yesterday. I only made it as far as when Kefka appears (the first time if you face him more than once), but I have some thoughts.

The first is that much of the level is fairly plain. There isn't much happening with the backgrounds, or platforming obstacles. I would have liked to see some more actual platforming in between character encounters, but I don't know how much time you had to make the level and you mentioned not being able to get all of the resources you needed, so I just assumed you didn't have time for everything and wanted to get the boss battles in.

The second is holy crap this level is hard. Now I have no problem with a level being hard. I actually prefer it to flying through them no trouble the first time through, but I think it's the wrong kind of hard for the most part. Almost every part I struggled with, such as getting past the daggers near the start, or Terra's Bio and Quake attacks was because I had to move forward and trigger the attacks and then move back before they hit me. Usually I didn't know they were coming though so I'd die the first time. After that it was often difficult to get the timing right because you have to react really fast, and because it was hard to judge when you went far enough to trigger them. The latter is due mostly to how plain some of the environments are I think since there were no landmarks to help judge distance. I think an easy solution would have been to make every checkpoint infinite instead of just some, because then at least you aren't stuck repeating the level when you screw up too much. I didn't mind starting over when I lost to the Mist Dragon my first time through, but when I died against Kefka and was faced with having to do everything again, even knowing it should be easier this time, I just didn't have it in me to do it again right away. Infinite checkpoints would have been a quick way to lower the frustration level while keeping the difficulty I think.

Those criticisms out of the way, there's plenty I like here. I liked the use of an intro, though it is a little long on subsequent playthroughs when you know the story. The sprite art was awesome, and on a conceptual level the representation of the characters, monsters, and their attacks was really well done. Overall it's a great concept and was fun aside from a few parts that got really frustrating. With some tweaking to the difficulty and more time to "pretty things up" for lack of a better term I think it'd be not just a lot better, but one of the better community levels I've played.