It has lots of positive features:
1. Clean, relatively scar-free trunk.
2. Nice trunk line, and even taper.
3. Branches in all the right places...evenly distributed, and appropriately-sized.
These features have to be quite conscientiously developed.
Some areas that will need some work to improve it's quality as a bonsai:
1. Nebari needs to be tightened up; ideally to compliment the branch structure. Several good ideas have been presented by some of our veterans: Thread Grafting is a good long-term solution. Planting it deeper is a good short-term solution that may provide longer-term results (roots may appear).
2. The branching is coming along, but don't let it develop "whorls", but keep shoots emerging in pairs. Photos are a good way to identify areas that are getting too dense.
3. The apex is a little coarse. Over time (take your time) you'll need to refine the trunk line so it's even. It will require you to wire thinner replacement branches into the right spot, and replace the thicker, coarser branches with thinner ones. This is a more conservative approach to reducing the height by 1/4 or 1/3 as some have suggested.
Here's a good example from a Kokufu-ten exhibition book. It exhibits many of the qualities your tree has, but a few years further along...something to shoot for!
