I bought this lens when I had the EOS300D (Digital Rebel)
I was utterly disappointed as almost every photo that I shot with the 300D were lacking in sharpness characteristic of most primes.
After I upgraded to 20D, I tried on the lens again. To my surprise, the lens took very sharp and good contrast photos similar to those taken with the 50mm.
I suspect it is the more accurate centre focusing point in the 20D which made the difference in sharpness.