I walk. I haven't had to make the connection for over a year now, but regularly did 1 to 2x/year in the past. It is usually easier to walk on the lower level - the sidewalk gets very congested on the departure level with curbside baggage check, etc. I never timed it, but I can't imagine that it ever took me more than 15 minutes, including stops for readjusting my luggage.