You looks like you are off to a good start for one of your first maps. You might want to go back in and fix a few places where your ramps meet your platforms. Click in on the R and L thumb stick to zoom in and slow the movement way down. Also you can use rotation snap to get objects at the exact angle instead of having to eyeball them. That way you can get a really clean look. Also I would advise you to put a kill boundary at the top of the map and not the grid. Just looks cleaner IMHO. The 3 level approach is good but I would add some more aesthetic stuff to dress the place up a bit.