Traded in my 30D for a 50D. I am an amateur photographer that loves to take travel photography. 50D is superb camera with many enhancements from 30D. AF is dramatically faster and more accurate, and the rear LCD is amazing. Overall, all aspects of camera is an upgrade. Metering is more accurate and provides less need for PP than 30 D did. Noise at higher ISO's is less (generally RAW processed with Aperture) than 30D, and up to ISO 6400 is usable...as it means getting the shot vs. not getting the shot. Sure there is a little noise, but Noise Ninja does an adequate job. Highly recommended.
There has been lots of controversy with this camera. Just go to the comparometer on Imaging-Resource, and you will see exactly what my results have been. Well controlled noise with great resolution.