I played the first and second level. The controls were quite a hurdle. The fact that they don't change based on your camera position is a big problem. It's very easy to get disoriented and not know which button will move you in which direction.
I didn't beat the first level because I found the invisible maze to be too frustrating. I didn't notice anything that would indicate an entrance to the maze, and only landed on ground briefly once or twice. Generally I'd fall off attempting to enter it, and I didn't really find that aspect fun in it's current state. I think if there was some sort of clue to at least get me started it would help. For example, I thought that the nearest cube would have a path leading straight to it to get me started. However, I fell every time I tried to go to it, and didn't know what else to do. I also tried this more times than I would have if I had a handle on the controls.
Level 2 was better, and I was able to complete it. However, the floor in it's current state is kind of a problem. The flat bright blue color makes it very hard to see changes in the elevation, so at first it wasn't clear which direction to go, as I guess the ramp blended in with the starting platform. It would also be nice if there was a shadow or something to make it seem like the ball was sitting on the floor.
But level 2 is where I started to see some potential for this as maybe a speed game of some sort. The big ramps on that level look like you could build up a lot of speed on them, though it feels like there's some kind of cap right now (or maybe the plain environment makes it hard to tell how fast I'm going?). Still, I like the idea of building momentum on them. The controls would definitely need to be more intuitive before that would work though. And maybe instead of the brake being an instant stop, and can slow you that way you can turn easier without losing all momentum. I think giving players tools to perfect a quick path through the levels is where most of the potential fun in this game lies.
So the takeaway: I don't think this game can be fun with its current controls. Address this before you do anything else. If you're going to edit visuals, start with the floor just because it's the hardest thing on the eyes and the only one that I think actually affects game play right now. I think there's fun to be had in coming up with fast routes through the levels, and it may be wise to design with that in mind.
Good luck!