It's hard to judge without more sense of scale, but the map looks huge. The spaces feel believable, but I think you've incorporated too much "verticality".
if you squashed some of these ramps down a bit, made some of the stairs a little less steep and the map generally flatter I reckon it would feel even better. You may lose some of the lower/upper levels, but I think the map already looks too complex* so that wouldn't necessarily be such a bad thing.
*an edited overview to show paths better is always nice, and using "mat_fullbright 1" casts global lighting so there are no shadows which makes things even easier to see.