I think it's a symptom of growing up in the 70's and 80's that I automatically assume too much screen time is bad. For us as kids, that meant TV, but we could certainly extend that into video games, computer time, and now tablets (probably phones, too). As a parent now I still have that mentality, but partly because I see other parents use screens as babysitters. Some kids can't go anywhere in a minivan without watching something, and others can't sit in a restaurant without a screen. If I'm being objective, I suppose these kids aren't being harmed, but I also feel like they're missing out on seeing the world they drive around in, or the people that move about their environment.
So with that said, I'm trying to keep more of an open mind. When I look at all of the time not scheduled for Simon by school, meals or whatever, I would certainly be concerned if that time was dominated by screens. He likes to watch certain shows, and we generally meter that a bit.
His new thing is the iPad. Diana bought some educational stuff, and I'm happy to see him engaging and figuring stuff out. Even navigating between apps is pretty easy for him. One game that has a lot of matching, color stuff, etc., is something he's getting too. He can even go between things in the game deliberately. He does get frustrated at times though, and that's probably his biggest challenge.