On the other, which at first I took for a floating shrine of white marble, is perhaps the most unique and graceful object of architecture in Siam; shining like a jewel on the broad bosom of the river, a temple all of purest white, its lofty spire, fantastic and gilded, flashing back the glory of the sun, and duplicated in shifting, quivering shadows in the limpid waters below. Add to these the fitful ripple of the coquettish breeze, the burnished blazonry of the surrounding vegetation, the budding charms of spring joined to the sensuous opulence of autumn, and you have a scene of lovely glamour it were but vain impertinence to describe. Earth seemed to have gathered for her adorning here elements more intellectual, poetic, and inspiring than she commonly displays to pagan eyes.I have to admit, when I went there I was much less impressed. As you can see in the photo, the chedi was not fully white and had lots of black sprinkles of mold. There's no significant Buddha statue and no lavishly decorated bot like in other temples, the only place which was more interesting was a pavilion containing a statue of King Rama II and with some murals on the walls. I just learned now that in fact this pavilion normally isn't accessible, so we were very lucky to be able to go inside. Sadly I only photographed the statue and did not shot the murals.
For some more information on this temple take a look at Richard Barrow's site, which also has a description on the annual Phra Samut Chedi fair.
Update: Richard has posted several more photos in a new thread at his forum, including photos of the murals.