First of all, before anything, I just want to say- YUM! That looks delicious.
I like the blurred background. It's a subtle effect, that only adds to the focus of the hot chocolate. I also really enjoy the pieces of chocolate. All the different sizes and shapes are interesting, and really tie in with the shavings on the whipped cream.
I like the layers in the glass. On the bottom, either due to chocolate settling or just the shadow, there is a small layer of darkness. Then there is the hot chocolate, which just looks yummy. That goes into a soft layering where the chocolate meets the whipped cream, and sticks to the glass. I like how from there, the whipped cream lightens into a sweet looking swirl. The tip on top is perfect. To me, there is a perfect amount of chocolate shavings- not too sparse, but just enough to add an inviting decoration and extra addition of flavor.
I like the lighting, although the lighting on the left look different then the lighting on the right. The one on the left looks more natural, and I feel that you should have tried for the same effect around the entire glass.
I also like that you included the tip of the spoon sticking out of the cup, although I wish it were more focused. The way it's blurred, it blends too much with the background for my personal taste, which takes away from the addition of it being in the picture. It almost seems out of place, it's so blurred.