We've been, the wife and I. To US/IOA that is. When we first came to the Orlando area in 2001, we lived about three miles north of US/IOA. We actually bought APs for there.
We didn't use them much. IOA is a great park for adults who like thrill rides. We don't. US is not all that interesting to us either, so we've not ever pursued getting passes again.
We did enjoy one of the earlier Mardi Gras celebrations. Went back on courtesy tickets a couple of years ago and it wasn't any where near as nice as the earlier one.
So, go if you've never been. It's well worth a visit.