Hey man

I like it, it looks cool
But the top right half/corner and border don't really look very appealing :/

suggestion to fix?

looks kinda lq, yo. take that border off too, yo.

quality is an issue yeah. the border is really thick, I usually try to keep it around 3px
try adding some light to your focal, and making it stand out from the background more.

blurred the background too much, needs some sharper background effects for better compo
the render has been over sharpened
borders are so 2008
and notice how there is lighting on his helmet, you need to create a lighting source. - if youre using photoshop -
filter > render > lighting effects > omni/spot (play with settings)
then -- soft brush tool (350-400px) > white > brush in same spot as the lighting effect.
have a look on deviant art at some tag tutorials.. everything you've done wrong will become apparent

Overall not bad. Its obvious you used a hard brush to erase the parts of your smudge that covered your masterchief. Next time try lowering the opasicty to 75% then to 50% then to 25% as you work your way outwards so its blends alot better.