I agree, even the 50 2.8 budget lens takes great pics. The only downside to the 135 2.5 is it's length, it can be a bit much for a walk around lens.
One day I took identical portraits using a FD 85 1.8 lens, the 135 beer can, and a Leica R 90 2.8 Elmarit (the latter had to go on another camera, couldn't fit it to the FD body). There was very little difference between them, which is pretty crazy given the price spread. They all made beautiful portraits, w/ the 135 giving a nice bit of compression, which is good for keeping the noses small.