I didn't find this as simple or trouble-free as the web page implies. Arriving at about 8pm, it was at least a 10-15 minute wait for the bus to the wharf were the water shuttles departed (which is far away from the terminals, near the Hyatt hotel). Then when I got there, virtually all the shuttles and taxis had already stopped for the night, with one water taxi left who took me "as a favor" (maybe a pitch for a bigger tip). All told it was more hassle than a taxi and not much cheaper, even given the outrageous taxi fares to/from Logan. Maybe it's better during the day.