I bought some some for my kids to get them into fly fishing, it was funny to watch my 10 year old walk down the river where people had been fishing all morning with no luck and see him catch 4 or 5 fish in 10 minutes (Granted, these are 5-9" trout, but still...). Grown men standing up on the bank shaking their heads and telling each other, "That kids got another one!" Still makes me laugh at the memory.
Not just for kids though, I think they're great for little creeks and streams where a back cast would be problematic, and less stuff to break or go wrong. Gotta love the simplicity...