Needed a sharp lense for many purposes (available lightning pg and outdoor portraits), this lens fills completely my needs regarding a medium tele for outdoors.
Use this lens sometimes for doing night clubbing photos with available light, along the 50mm f1.4 (are my two main ammo for this kind of work).
The quality of the lens allows you to shoot almost wide open (in fact mine lens peaks around f2.5). Many people blames about lens flare - use the hood! is ugly but makes their work well done. For many people this lens will rival with L counterparts without the associated expense of L primes.
With subjects between 2 and 3 meters of distance is their preferred distance, you can blurr the background magically going wide open.
The focusing is quick and reliable. It doesn't hunt nor fails (and you can ever focus manually thanks to the FT-M).
Many people asks to choose between the 85 1.8 & 100f2. For a 1.6 crop camera you will be quite happy with the 85 (around 135mm). If you insist on film (1.3 crop of FF), your best bet is the 100 or the 135mm.