Pretty good, but instead of a graphics tablet you could use synfig and avoid frame by frame animation entirely. The process would be to construct whatever you wanted to animate with vector regions instead, by tracing your rough sketch with a vector region.

It would take time to learn but you could start making better animations in less time without having to invest hundreds of dollars into new equiptment since synfig is free and has a lot of the features of more powerful adobe products.

If you have any questions or look at my work and wonder how the heck I did something I'm more than happy to share.

Otherwise keep it up and if you need nice looking color pallets heres a resource for that too at:
http://paletton.com

Really smooth animation, well done. Unfortunately I know EXACTLY where I remember the song from.