The composition on this photograph is good... I like the red color of the Coke can agains the dark background. Red always stands out very nicely.
The primary problem with this photo is the focus. There is no reason that I can see for it to be out of focus. Soft focus should add some interesting element to a photograph. This photo resembles product photography like you would see in a magazine. Sharp focus should be part of this image :)
Too dark and not a very clear focus. The red doesn't look authenic. The cropping being just a hair off center is distracting - either centered or more off center would have been better. This is my favorite drink and I have one right now. That's how I knew it color was off, for sure. And these are just my personal opinions.
needs to be sharper... if your camera has a macro function you should use it... if not, you can take a magnifing glass and hold it near your lens to sharpen things up a bit...