I was never a fan of my 28-135. Replaced it with the 24-105 and am much happier.
I should hope so, considering the price differential....
For the record, I bought a 28-135 IS at Christmas on Craigslist for $125 Canadian. I'm impressed, though no doubt I'd like to have the 24-105 more.:o
For the money, the 28-135 is sharp wide open on my old Canon 1D Classic.
It works well as a walk around lens for me.