The starting spawns are cool, how they light up but I really dislike the actual chest area because it just doesn't look right. The terraforming on this map is different, in a good way. The land forms weak ligaments which is a change to what I usually see people do when terraforming, it's really nicely done.
The map needs more structures also, the only one I could find besides the cornucopia is the crashed plane (although really nicely built). The terraforming obviously is what this map showcases but it would be good to have just a few more structures built with the land to avoid dullness. The waterfall, mountains and overhangs are stunning.
Two more things I might touch on is the glowstone lighting could be changed into something more interesting, and from some positions of the edge of the map players are able to look out to see the superflat would which, although not important, can be argued to take away a feeling of the map. Good job on what you've done, the waterfall especially is quite awesome.