I was thinking that this was a pretty good idea for kids who can't shuffle. I've bought one of these device and they work pretty well. I think kids would also have fun pushing the button down and seeing the cards shuffling themselves. What do you think?

They're okay. Sometimes they jam... and the kid's might find using it to be more fun than watching the show. Using the shuffler might be a fun diversion, but it might also end up being a speedbump in the flow of the show.

Are you talking about kids who are too young to know how to shuffle or kids who are injured or disabled such that they can't shuffle?

If it's the former, I have to ask what kind of card trick(s) are you doing for kids who are too young to be able to shuffle. When I choose card material for kids that young, shuffling isn't an issue, i.e., randomizing the cards or losing selected cards in the deck isn't necessary.

If it's the latter, I'd still try to simply not make shuffling an issue. If your audience members can't shuffle -- kids or adults -- just do it yourself.