I'll note that I took this bus a few weeks ago on my way to the US (happened to be in the area, and it was actually easier to jump on at the Ginza stop than trek over to Tokyo station for the N'Ex) and was quite impressed. Like the others, only a few passengers -- and almost everyone got out at the first T2 bus stop for the LCCs. Only two of us went on to T1, where the stop is right in front of the south side terminal.
Unless there's ridiculous congestion, this basically runs at the same speed as the N'Ex, and for a third of the price. Recommended.