xD I'd just like to mention I actually tried out holding a cup like that (checked in the mirror) and it's actually not uncomfortable, unless you hold it for a REALLY long time. It's the hand shape you make when offering a friend I drink I think...

The only I have to say is when I added a straw into the equation, it was either in my mouth and my hand hurt, or it wasn't and my hand was comfortable. I think it's the straw is off...

also the right hand is a little small sorry ^_^;

Love the coloring though o:

Well, first off, this is a very nice piece!
The angle is a good change and the clothes seem nicely detailed for a bust-esque portrait

I feel that the eyes seem too far apart.
I am currently studying faces in art, so I can just fully say that part is off because on any human face, eyes are not that far apart.
Even though you drew in manga style, and I know it doesn't have to apply to realism, but that just feels off.

Also, the hand "angle" feels wrong, too.
The fingers seem to be grasping the glass at an angle that seems difficult or impossible.
Maybe next time you draw a hand holding a glass, use yourself as a model, or look up photo or pics on Google.
References always help an artist grasp a concept

And lastly, the items themselves don't seem that 3D. They need more shadow depth to them or brighter lighting.
Contrast always helps a great deal with objects

Well, I'm sure that I said the same things as the other critiquers pointed out, but I hope this helps