yes, my 2 yr old and 7 yr old have and love theirs... it is best to get them each one of their own to prevent rivalry, and it is fun, educational for them, and at times they will entertain themselves for hours at a time... pretty awesome... but for the young one, avoid the simpsons game, as i am always getting asked for help jumping around... heh
i dont advocate screen protectors, but if you feel the need, they are cheap enuff, but i dont feel they are needed... just teach them to be gentle.... and get ds phats, not lites, they have yet to hurt theirs... but you should tether a stylus to it tho...