Great buy mate, 135 on a FF - is just some magic.
I've always had focus inconsistency with mine - it is an early copy though and to be fair was probably always with the 1D rather than the 5D.
It's super sharp at f/2.8, if you can be tempted away from f/2!
Christian Wright; Dip Phot
EOS 5D Mark III | EOS 600D | EOS-1V HS
L: 14/2.8 II | 24/1.4 II | 35/1.4 | 50/1.2 | 85/1.2 II | 135/2 | 180/3.5 Macro | 200/2.8 II | 400/2.8 IS | 16-35/2.8 II | 24-105/4 IS | 70-200/2.8 IS II | 100-400/4.5-5.6 IS
580EX II | EF 12 II | EF 25 II