I think you just have to ask yourself what your expectations for that playfield are. If you're looking for a 'perfect' playfield you're not going to get that with what you got there without a TON of work not many people are capable of.

One option is to install a hardtop. It's still a lot of work, but yields great results.
http://www.outsideedgeproducts.com/store/p75/Pinball_Playfield_Hardtop.html

Another option (and the one I'd go with) is to clean, buff, and wax what you have there, and enjoy it. For cleaning I'd use magic eraser (carefully) with naptha to get the deep down dirt and ball swirls out. Followed by a good buffing with a machine and compound on the existing mylared areas to get them shiny. Finish it up with a good coat or two of a carnuba wax.

Hope this helps

-Paul