I have kids who watched the streaming service every now and then, but still canceled it and went Blu-Ray/DVD only because, in my opinion, 99% of the streaming content is awful. It's like the old cheap-rentals section at Hastings.
The selection for kids was just a bunch of the same cartoons the networks re-run all day long every day on cable that we don't like them watching, so it didn't seem to make sense to pay extra so they could re-watch more of the same junk more often.
If you have them, it's worth it. If not, it's harder to justify.