PCWatch has a comparison between the *istDS, *istDS2, and the *istDL.
It is in Japanese but the online translator that I have to use is not
exact enough for a general translation.
http://dc.watch.impress.co.jp/cda/longterm/2005/09/30/2390.html
One sentence stand out, however; not only is the display of the DS2
larger, the menu text is larger too, making it even easier to read.
There seem to be a [very] slight improvement in the SD card writing
time in the DS2.
Of special interest to the non-Japanese speaking person are two sets
of comparison shots for the three models using the set 18-55mm lens.
A number of macro shots from the DS2 using the DA 50-200mm and the DA
50mm Macro concludes the article.
This article is the last in a series of tests of the DL. I have
collected the other links on my *istDL page: http://mac.tidings.nu/
PinkyPentax/istDL.shtml