Eh, not bad.
May I offer advice? Use the shift key for straight lines and for shading it is easier to use the pen tool and fill tool combination. Also tweeting is nice and I see that is what you mainly focused of but it would add more life to your animations if you made your characters move within that symbol that you 'tween. (make yes move, head turn)
No onto my opinion. I believe that you need to work out a few kinks still and that is perfectly fine. I am still working out mine as well. But, you cartoon seems bland and It was unclear as to the story you were trying to convey. I enjoyed how you tried to add a 3D feel to the animation but when you zoom in the background should zoom as well.
Over all I think you just need to keep practicing and refine you skills and technique. Animation isn't very easy and sometimes people will ridicule your hard work, but do not let that stop you from doing something you love to do.
Keep at it.