First things first, 'Miniature Walcheren' is now known as 'Mini Mundi' so that should be corrected.
We visited Mini Mundi last summer (2012) while we were camping in Retranchement. We purchased tickets online (EUR 36,14 for the 3 of us) and took the Vlissingen-Breskens ferry, a train and a bus to get there. Public transport to and mainly from the park is terrible. The park is open till 8pm while the last bus goes just before 6pm which forced us to hitchhike a ride to the station (thank you, lovely German family!).
Okay, about the title: it's a tourist trap because the food and drinks are insanely priced and offer little quantity (quality is ok - not great). Maybe this is typical for an amusement park but Mini Mundi is more like an oversized playground. The park itself was a complete disillusion for us. It's fairly small for the price, the miniature part is mediocrely maintained, the giant part is surprisingly tiny (expect a big chair and table), the attractions are not continuously open and the cool electric train needed to charge for an hour before our kid could take a ride. The indoor part is fun but beware the slide that goes straight down, it's not suitable for all children (I had a blast though)! Overall it's a modest clean park with friendly staff that doesn't really care for you that much. Your children will have a good time and you can relax with some overpriced drinks or a game of pinball, expect nothing more. I do see the potential in having a kids party there or having a subscription if you live nearby to escape a boring day with the kids but from a touristic perspective, I would avoid a trip to Mini Mundi.
If you own or manage Mini Mundi, register now for free tools to enhance your listing, attract new reviews, and respond to reviewers.