I would write a critique, but im not a premium member, so i'll write it here.
The edges around your body are very rough and seems like ur using either eraser tool or not masking properly. besides the edges being rough, you got a pretty good general outline sense. another issue is i guess the directional lighting. you have great lighting in the front, but does not match up with the background lighting you have used. that is just a photo lighting error, or not keeping that in mind when you selected the background. the waves look really good, and does really resemble water, so props to that. the glow trail looks pretty good too.
so yea, overall, good use of photo manipulation, just need to clean up ur edges better. =]