This, obviously, is not a real popular lens. I think one of the reasons is that the 100mm f/2.8 macro has stolen a lot of this lens's thunder. Never-the-less, this is a very good lens. It does have an issue with CA at f/2.0 in extreme contrast, but not too bad. The copy I have is extremely sharp @ f/2.0. I bought this lens for $300.00 on EBay.

Thank goodness for the popularity of the 100mm f/2.8 macro!
Canon 20D : 100mm :1/320 sec : f/2.0 : 100 ISO : CA uncorrected
Canon 20D : 100mm :1/200 sec : f/2.8 : 100 ISO
These photos are direct raw conversions using Lightroom 3 defaults, then sized down.