I don't play it but my kids do. I have actually had a blast driving and walking around with them. They usually go in there rooms, shut the doors and only emerge for nourishment..lol
When you see groups of people in one area, that usually mean someone has set an "allure module" at a location, which lures the pokemon to the area.
We were actually camped out at the cemetery one night with about 40 other cars. It's silly and stupid, but we had a blast. Not going back though...lol
I'm waiting on it to start costing money, then I'm shutting it down.