First, it lets you maintain a sorted database of your favorite places. That’s something I enjoyed about Gowalla. Rego also lets you identify places you’d like to visit. That’s what I was using Stamped for before it folded. The main difference between the three is that Rego is not social. You can opt to share a spot, but that’s disabled by default. I like that a lot.
I’m going to play with it for the next few days and then I’ll post a review to TUAW. Look for it some time next week.