I have had the 70-300 DO for about 12 years and find it to be a lackluster lens and seldom use it (never).

https://www.kenrockwell.com/canon/lenses/70-300mm-do-is.htm

I agree with Ken Rockwell's review of the lens except I add that it just doesn't have the color and contrast "pop" of equivalent lenses such as the 100-400 L II zoom. One thing, though, the used price for the DO lens is low.