We expected to see a few wind-mills then go on with our trip, but we finally spent a few hours there.
An interesting video (multi screens) explains the site. It was quite funny as well.
The visit of a wind-mill itself is impressive.
We then had a nice walk around the site, along the canal, watching ducks, wind-mills and an overall beautiful scenery (full of tourists, but this was not disturbing).
It is a pity there was no proper place to have a nice cup of coffee on the site.