Bug-fixes and new features, all in an easy-to-install pop-out ROM package, as well as compatibility with later versions of the OS like 3.9. Well worth the princely sum of around $20 USD, at least for me. 
Completely useless if all you want to do is run Whdload games. I'm not against 3.1, but for Whdload games only it's just not beneficial. It's not even about the cash. It's about having to install this, which means messing around with the mobo for no good reason at all. Just leave it be.
Don't recommend things that people don't need. I'm surprised no one has recommended a 68060 yet :lol: