Given that the current invoice, shipment and credit memo PDFs look the same as in Magento 1 and PDF's are always a bit of a nightmare to customize for the merchants:
I suggest to replace the PDFs with a html2pdf tool. Actually the preview of the invoice looks already really nice in the backend, so this could just be converted to pdf.
This would maybe also help the problem Hirokazu Nishi mentioned in his tweet:
"Magento2 still use LinLibertine font. It’s only for Alphabets. To change PDF font, we still have to rewrite some classes..."
This idea resulted from a tweet/discussion here:
Yes please! At the company I work for we've built an implementation with H4CC Wkhtmltopdf and Snappy php wrapper.
It works brilliantly and isn't too heavy on the server.
Also built in a caching layer saving the PDFs to S3 but that's just being fancy
Right now in Magento 1 we've implemented the PDF's as the emails, with local templates and a variable engine generating the HTML, the actual PDF renderer (snappy) is ambiguous
It's not only font file. Printing some characters that consist of both single-byte and double-bytes, we have to calcluate each words width correctly. Otherwise they are sticking out from rectangle area!
And also Zend_Pdf can't generate PDF files without font file. So multibyte PDF (especially Chinese and Japanese) becomes huge size.
Just found another case where someone would be happy about a HTML invoice PDF:http://magento.stackexchange.com/questions/154693/magento2-html-invoice
We have created https://github.com/EaDesgin/magento2-pdf-generator2 some time ago. Maybe will help somebody.
Also supports right left and asian fonts and languages but they are not implemented not implemented.
Magento 2 PDF Customizer ← We have a solution
With this extension, you can make flexible HTML+CSS so to create PDF templates.