After owning this lens for a year and having recently sold it. Here are my thoughts regarding this lens as I look back.
Fist start off with the Cons as they come to mind:
-Price: I'm a firm believer in the adage "You get what you pay for". I still believe that to this day and this lens offers incredible picture quality. But that being said it's still a lot of money and it's high price is probably the number 1 reason most people don't get this lens. In light of recent events the price has gone up even more.
-Slow as an 18 wheel semi truck merging onto highway traffic AF speed. It takes some getting used to at first and I still never got used to it completely. The AF is slow. Don't let other people tell you anything different. It is hard to track moving targets with this lens and the lens should be used as a pose and shoot portrait lens. It's very hard to do much else considering the speed.
-Focus by wire manual focus. Never completely got used to this either. The focus ring felt very loose and it was hard to get a good feeling for it.
-It's a big lens. Let me tell you I love glass and this lens has a ton of it. When someone is staring down the barrel of this piece of glass they can tell right way it's a serious piece of equipment no questions needed. The problem is it's also big and heavy, and I would consider it close to par with a 70-200mm in terms of portability. You need a lot of space in your bag to carry it around.
-No dust and weather protection. Am I being anal? Probably... but for the amount of money I spent on this lens would you be too? It's pretty easy for dust to get into the lens. After owning this lens for only a few months I noticed at least one spec in the rear element. Probably didn't make much of a difference in the pictures, but it was there in the back of my mind.
Now lets talk about the pros of this lens:
-Freaking unbelievable pictures
-"Are you kidding me??" pictures
-Holy cow!!! pictures....
I think you get the point....
Well I recently I ended up buying the 50L it's only been a few weeks with it but I'm pretty happy. I think I'm a little more comfortable with the focal length and since I own both crop and FF body the 50 would fit them both equally well. Whereas the 85 might have been a bit long for the crop. The other issues I had also seem to be alleviated at least. I just hope the 50 can come close to the images the 85 had delivered. The 85 is just an amazing lens and just having this lens can make you an amazing photographer (plus a little bit of skill involved) Another reason I sold the 85 was I recently got the 70-200mm f/2.8 MKII and it's probably the best zoom ever made. I just couldn't keep both.