Multiple tips:
1. This map is ridiculously long. Long maps can be fun, if done perfectly. There has to be an interesting thing to look at or do throughout the entire map that is different from the last zone. The map might work better if something like this was split into two maps, since you expect it to be done after you finish the first boss.
2. Obstacle spam is a problem. During multiple parts in the map, it is easier to go around some tracks than actually going through the obstacles since it's just stupidly difficult. Obstacle spam makes it really hard to enjoy a track because all you're doing is dying. Also, don't use those spike throwers, it just blocks the path.
3. Visualwise, some of the things were kind of neat, but you have a fog problem. Maps look bad when it's all fog, turn the minimum and maximum fog distance up in the editor, and it should look nicer.