For me is working fine but the PDF export (only available if you don't use the HTML editor).
Going back it is almost imposible. The standard wiki never "read" the tables of Nwiki (the code is from 1.5 withouth changes). The dfWiki team gives support for new upgrades of NWiki.
Both wikis never coexist (the use several tables/files with the same name). If you dont remove the original wiki folder before install Nwiki you will have problems.