I bought my body used fourteen months ago with 9000 shutter clicks and been in love ever since. Never had a problem. The build is excellent for this level of camera (semi-pro). None of the bells and whistles like video and an articulating screen but those seem more like gimmicks than anything else for my purposes.
I opted for a used 40D over a new 50D and with the extra cash bought an EF 85mm f/1.8. It is a great combo! While the 50D does have Digic IV I cannot see any difference in IQ between my camera and my friend's 50D with the same lenses attached. With his 17-40mm f/4 L this body really shines!
The only way I can see myself giving this camera up is if it cannot be repaired for less than an equivalent Canon body or I decide to go full frame. If you have the chance to get it then grab it!