It's a nice park on the water. We don't have a lot of these in AZ!
There are 5 miles of multi-use (bike, walk, run, rollerblade, whatever) paths. You can reserve a picnic table, rent a boat, spash in this water thingy during warm months, and take a nice walk. It's a fun place to go kill a few hours, it's free, and it's close to Mill Ave. Kind of hard to go wrong!