Full Review

Been using this camera for about one year. I had already a few Pentax lenses and this was the first "affordable" DSLR form Pentax, so my decision was clear. This camera was a must for serious amateurs who came from analog Pentax world and wanted to go digital. It is also very good in comparison with other brands cameras in this price range. Today there is Pentax DS2 with some improvements over its predecessor, but with firmware 2.0, the Pentax DS is still very capable camera.
I am very satisfied with it, as it steadilly gives me very good results. Most of the important things for me were the compactness of this body, ability to use old lenses, easy to use interface, standard power source and a very bright viewfinder.

PROS:
compactness - very small camera, but very good for handling (which I can't say about Canon 350D, where the space between lens and grip is too small for my fingers). Nikon D70 has even better grip, but it is way too bulky and heavy for me.
bright viewfinder
ability to use old lenses - meters with all K-mount lenses and also with M42 lenses mounted via adapter
standard power source - 4 AA or 2 CR-V3 (some people use also RCR-V3, but Pentax don't recommend this)
good picture quality - on par with Nikon D70 as it uses the same chip from Sony. Low noise level at high ISO, although I prefer shooting by ISO 200, which is the lowest in this camera
large and fine LCD (210000 pixels)
Pentax support - 3 firmware updates in one year, the last update (v. 2.0) brought some of the most desirable functions from DS2
well balanced and practical features for the price
flash compatibility - can use older TTL flashes as well as newer P-TTL ones

CONS:
slower AF with kit lens in low light - but this is common over brands in this price range and depends heavily on lens; the AF is quite accurate
some people complain about JPEG quality, but I shot no JPEGs (shooting all raw), so can't comment on this
"crippled" K-mount - with non-crippled K-mount it would be even easier to use old lenses, now I have to push one more button (not major issue for me again).