they only have small overhead storage, so if you're packing heavy there might be luggage storage issues. I'm always surprised when trains that make the airline run don't have room for baggage; this happens all the time on the Blue Line to and from ORD.

Also, I just assumed that a train as well-known and well-patronized as the N'EX would run all day long every 20 or 30 minutes. Lucikly I got lost in Tokyo Station one day and happened upon the posted N'EX schedule and discovered there was a big hole in the mid-afternoon when I had planned to just show up and get on board. Made me rearrange my whole trip to NRT schedule, and naturally I got to the airport ridiculously early with hours to kill. Lucky for me, the "amazing" beer machine at the UAL RCC filled the time.