So far - it's pretty much the same
I guess if I had others subscribed to my calendars or whatever, I might find it significantly different. Right now, I'm just relieved it works well/fine. I didn't even know about the free upgrade, but did upgrade at 50% off before the end of March. As it allows syncing of to do lists to the iPhone, and I use the To do lists for memos about a number of different things (like terminal commands to make OS X behave as I want it too), it's important that I retain those. I really haven't used the new features. When/if I do, I'll update.
I do appreciate some of the configuration options like being able to change the standard meeting time from 1 hour (to in my case 1/2 hour but other options exist). So there are improved configuration options which I have used/