Bought these for my 4 year old who bizarrely, is particularly fussy about headphone comfort. They fit very well and there is plenty of adjustment room for different head sizes.
The sound quality and sound limitation is very good. The only major downside (as others have mentioned) is that there is no automatic kill for the limiter switch if not in use. Presumably this would be difficult to manufacture, but it does mean that your child is bound to forget to turn the switch off and you will burn through batteries quickly. If it's left on regularly overnight, you can expect to replace the battery within a week.
They are fine for small fingers and they can take a bit of beating. The headphones have been dropped, jumped on and spilled on and are still going strong after six months.