We were there last weekend before the festival. It has been going on for years. It is a dutch settlement. If you go to the windmill you can buy tickets that include a video with the history of Pella, a tour of the windmill, and a tour of the village and a miniature village. The tulips were not in full bloom when we were there, but still a lot of tulips. There are 2 bakeries with dutch pastries. Yum.
I've stopped several times and even a few years ago, took foreign language lessons from a native speaker who lives in the area. Each visit, I've found the staff helpful. The library is clean, quiet, and well stocked especially considering the size of the town.