Although responsive is nice, I find the update too stripped-down. I'm not a fan of the low-contrast (ios-style) movement in UX.. also it removes many links/buttons/features so that it looks more "simple". I'll take the ability to click on things in the original over the fancy transition effects.
There is a plugin for the modern TiddlyWiki (IIRC it's full name is TiddlyWiki5) called GSD5 (GSD is for "Getting Stuff Done"): http://gsd5.tiddlyspot.com/ .
I've never used TW Classic and original mGSD, but GSD5 is "heavily inspired by mGSD" and on first glance they look alike a lot.
And, anyway, TiddlyWiki5 with GSD5 rocks.