Nice start. It does add to the feel of the cave atmosphere. The thing I think that I notice though is that it seems a bit too sharp and artificial. That's probably the bevel though. An idea might be to do a height map instead of a bevel. All the solid rock areas would be max height while the cave paths would be low points which rapidly but smoothly moved towards the high points.
Here's an example of what I mean. Not exactly the fanciest since it was rushed but it gets the idea across (I hope anyhow).