Parents need to know that this site is chock full of ads. There is a banner ad at the top, a banner along the side, and a smaller ad along the bottom of each page. They aren't just static ads, either; they move, flash and are generally distracting. What is more annoying are the occasional interstitial ads that pop-up when you click on a game you want to play. The ad pops onto the screen and stays there while your game is loading, forcing exposure to the ad -- you can't just close a window like you can with a "regular" pop-up. There are "pop-under" ads that arrive, too, silently lurking behind your main browser window. The games themselves are fun, if you can concentrate on them with all the flashing adware competing for your attention.
The games on here are mostly fantastic, but my son just asked to download a Dora Carnival game. I checked out the site and it looked fine, so I told him to go ahead. When we opened it to install it, the game actually came from WildTangent, and that's a site with frequent virus problems. NO WAY am I going to let him install something from WildTangent. Primary Games needs to sponsor different sites.
The science section contains no true science. It is simply creationism hiding under a claim to be scientific. Suggestions that man and dinosaurs might have roamed the world together. Children should not be exposed to this rubbish.