Your translation "Of particular interest to the children is the water slide" is actually quite good.
In terms of style, this is an awkward sentence. I could imagine reading something like that in a local newspaper where some amateur journalist publishes a report on some local sports club's summer festival or so. Such writers tend to use very artificial or bureaucratic style. A more natural way of saying this would be:
Die Kinder finden die Wasserrutsche besonders interessant.
Bei den Kindern ist die Wasserrutsche besonders beliebt.
Besonders beliebt bei den Kindern ist die Wasserrutsche.
Die Wasserrutsche ist der große Hit bei den Kindern.
In oral communication you would most probably say:
Die Kinder finden die Wasserrutsche toll.
But "toll" would usually be avoided in written language.
