The compression engine of 1.1.1 is more stable than 1.0.2. The old version reportedly compressed more the further into the movie it got, where the new version doesn't; it's more uniform.
Besides, it's a free upgrade to registered users! If you're in doubt as to how much you'll like the 1.1.1 version, just keep your old one on hand so that if, for some reason, you don't like 1.1.1, you can simply go back to using the version you've got now.
Plus, if you ever find yourself wanting to back up an episode DVD -- and for that, you'll want those menus -- you'll have that freedom.
Whatcha got to lose?