For the first time in my travel history, I was on a flight on Thursday night that offered Wi-Fi server (after reaching 10,000 feet). I was on a rather short flight from ATL to GSO, but thought that I would give it a shot. There are some sites that you can check out without paying a fee like your travel plans at delta.com and some basic news. I checked my FF activity and the miles for the flight that I was actually on were already posted. I also checked out some links to news stories that were popular that day. Without paying, I can't surf around where I want, but I was comfortable with the speed of the connection. The ads equate it to mobile broadband speeds. From my experience, I'd say that is a fair assessment.
For a short hop, I don't see the big value in paying about $10 to be connected for such a short amount of time, but on cross-country flights where it may take 4-5 hours or on an overseas flight, this service can be valuable. Although it is good to be forcible disconnected from time to time, this service will make my time in the sky more productive. Would you LIKE to stay connected when flying?