While aquascaping is 100% personal preference when it comes to what is aesthetically pleasing... I can give some observations...
1. It looks like the rock is very close if not touching the side. This will be very difficult to clean and over time may not look the greatest from the outside.
2. This may be the angle of the picture, but it looks like you have limited yourself for coral placement to the top of the structure. I would suggest making it more terraced to give you multiple layers to place corals on.
Just some thoughts on the structure. I have redone mine so many times in the past, I wish I had images of each time I changed it. It is kinda crazy the evolution of our tank aquascapes over time ;)