I used to watch this show when I was little, as it was one of those shows in a line of kids shows that play on kids TV after school. So in amongst the likes of Thomas the Tank Engine, Nelly the Elephant, and Postman Pat, I used to watch this little show. And I always found it really scary. Absolutely terrifying. The weird puppet things are hideous and the whole show just has a very freaky feel to it. While I can look back at Nelly the Elephant, Thomas the Tank Engine and Postman Pat and think of them warmly, The Riddlers just sends shivers down my spine when I think back of it.
Some kids may like this show, but sensitive kids, and most little kids around the ages of about three to six are sensitive, will find it pretty scary. Even know, it sometimes gets bought up in conversation, "Remember that freaky show we used to watch when we were little..." Overall, I'd say it's probably best to avoid this one. It'll give your kids nightmares.