I don't think these are great at all. Our children are already becoming computer and video game junkies, and there are already many great children's websites with point and click educational content that is very similar.
If everything we give our kids blinks, makes noises, responds to point and click, who are we to complain when they think plain old books are boring. My son is only getting conventional children's books. Plus this takes away one of the biggest aspects of reading to a young child -- the togetherness. He sits in my lap and we don't always read the books, but we point to pictures and talk about them and I ask him to point to things. He loves turning the pages and picking where in the book to look. And if he's really in an un-wiggly mood we read them.
Perhaps it's good for travel distractions, but a bit too expensive for me just for that.