I had used both EF85 f1.8 as well as its brother EF100 f2 for a couple of years.
My experinces is a bit differences from most forummers here as I found the 100 f2 is slightly better, because I do not see the purple lines when pictures has stronger light source.
Both are fantastic lenses, not heavy (not light either), super fast in autofocusing and most importantly will get you very high success rate of in-focus pictures even shot at wide open. My experince is near to 10/10 success rate.
As most has noticed that its only complaitable weakness of such lenses is.... That's no red ring on it. Thus it is not a L lense.
If you can live with a lense without the Red L ring, then go for it. It is one damn fine lense.
--
EOS 30D, EOS 40D, EFS17-55 f2.8 USM IS, EF17-40 f4 USM L, EF70-200 f2.8 USM L, EF100-400 f4.5~5.6 L IS, EF50 f1.4, EF85 f1.2 USM L II, ST2 & 580EX II