I have the macbook air 11 inch and I like it. the only problem is that I have to pay money (tethering) to get large screen broswing and a real keyboard. So I like the lapdock because I don't have to pay 20 bucks a month.
also, about the battery, the macbook air has a 35 watt hour battery and it is a lot smaller. I am thinking that they could have put twice the amount mabey even 3 times. there is no actual computer in the lapdock. I am doing a battery test now.