Got this from my dad. He had a EOS II film camera, the kit lens, and the 75 - 300 zoom. It has to be at least 10 years old and has no USM. Pics from it have looked good to the untrained eye though IS would be great to compensate at the long end and lower light. However, this older version has looked good so far. One area it is very good on initial tests is to have it attached to the camera body and use a reversing ring with a 50mm prime attached to the end. Picked up a cheap eBay 50 mm prime for $10 and reversing ring for $8. Now I can get nice macros on my 20D anywhere from 3:2 to 6:1 if I can get good light. Really a great way to use such an inexpensive lens. Did not notice any vignetting on my 1.6x crop sensor.
Besides, how can you appreciate the best if you haven't used the rest first?