COMPOSITION This photo IMO could have been composed better. For example, the rule of thirds - your squirrel is neither centered nor is it in one of the thirds - it is just, well, there! That's quite distracting for me.
BACKGROUND Your background is very bland which in some cases can be good but it is just too much for me here. Maybe a tighter crop would have worked better or as has been suggested, a whiter background.
CAMERA WORK Well, the shape of the squirrel is definitely there and the silouhette is done nicely, I just think that there could have been a few changes to help enhance the photo!
MY OPINION This is not the sort of photo thaat I would personally go out and buy to hang on my wall. It needs that 'WOW' factor and IMO it just doesn't have anything special about it. Keep trying though and if you have any questions or comments about my critique feel free to PM me.