sweg wrote Please rate and tell me what you think. Spent around 8 hours. My first design ever.

Just letting you know of what I think about it like you asked for & criticism is for you to get better buddy.

Well ill start of with a rating, id rate it 3/10.

This isn't to be mean, its just there is a lot wrong with it, BUT these can be easily fixed.

First of all you really need to work on your blending. The background stocks are blended okay but need work, and the character images need a lot of work. The guy on the left should be faded in not cut off.
The 3D text also needs to be blended in as it looks like its just been slapped on top of the piece.

The colour scheme is a nice idea but its a bit touch and go. Those shades of blue and green i feel don't work well together. The 3 white lines i would remove them.

Finally a colour correction layer can really change a piece around! You need to change the colour correction big time. It makes the people look odd, slightly Hulk like Try to go for a slightly softer CC and see the result.

I know its your first attempt so its not bad, iv seen worst, but there is plenty of potential. Good luck in the future though!