This is a very busy composition with a lot going on. For me, the repetitive nature of the "Heart" trees and the floating islands is not working. The clouds opacity's are inconstant making some look like clouds and other like cloud shaped fog. The trees in the foreground have been poorly selected from their original image but it actually works for this image lending itself to an "other worldly" feel. I get the Avatar reference, but the waterfalls do not look natural, again they look like some of the clouds, and appear too transparent. I'm not certain if you have a huge floating glass sphere in the sky or a distant orbiting planet with a uniform surface. There are some light rays coming in from the upper right hand side that for some reason come to a complete stop right above the mountain peak. I do enjoy the color scheme, the green grass on the floaters is complementary.
All in all, not a bad comp. A little more planning and plenty of practice.
At first sight your composite had a 'Wow' effect on me.
But when I had a closer look and detected the many flaws in your work, I couldn't get rid of the feeling, that you just want to impress forum members with your 'beautiful piece'.
I might be wrong, but I think as an artist you should create solely for yourself.
The forum is just a 'tool' for judging your PS knowledge, but gives you a idea where you could improve your work.
I do not want to IMPRESSSSSSS any body. The ones whom I wanted to I did already. Besides that I love taking suggestions sportingly, and at the same time I am proud that I atleast I can make my critics go WOw some times
You have to remember that it's easy to impress people who don't know any better or who are afraid to tell you otherwise. No one is saying your bad, you need to learn from your mistakes and show improvement.
You have one of the farthest floating islands (red arrow) equipped with a water fall (yellow arrow) who's water is passing in front of clouds that are located in front of a closer floating island (green arrow).
It should look more like this and pass behind those clouds.
I'm no photoshop master, so perhaps that's why I am impressed? Jokes aside I also appreciated your use of an opposing color from the color wheel to your main color scheme, in this instance the green grass to the over all purple theme. I think the opportunity to bring orange into the piece to balance your work was missed though since obviously you have a "natural" light source shining from right to left in your piece. From the perspective of an art student I just think a little orange helps to eliminate that initial impression of "Oh wow that's purple."
I also noticed the M C Escher tree in the back with the water fall that deifiers linear perspective.