I am not sure why, but my Air base model seems to disappoint. 1. I've had a flickering screen more than 3 times now. It is something I've never experienced in any computer I've ever had. 2. Almost every time I wake up the computer from an overnight sleep, I have to restart because it simply doesn't respond. And even if it did, I'd have to wait at least 15 to 30 seconds for it to respond. That's a little disappointing so I've contacted the Apple store and decided to get the refurb ultimate. I hope I'm not disappointed with that one too.