Good but old. (5 years now)
The new 450D has twice MP count. Find megapixels mean relatively little providing the camera is over 5MP, but it just gives you that extra cropping ability. It's also 2.5 photos a second, compared to 3.5 of the new 450D.
However if that's of little importance for you, and the 300D is being offered cheap (perhaps with some good lenses) then it makes sense. If it helps, on eBay a 300d body only goes for around £150, around £200-250 with a basic lens and memory card etc.
DP Review have a good article, review and example gallery:
http://www.dpreview.com/reviews/spec...on_eos300d.asp