This relatively small and light 135mm is hailed as one of the better lenses out of Canon's 'basic' FD line-up. It's sharp, contrasty as long as you don't shoot into the sun, and at f/3.5, it trades some speed for portability. Still, f/3.5 is more than enough to avoid blur in daylight shooting.
The 135mm focal length is very useful; it produces beautiful portraits and is long enough for candid portraits too. It's an interesting change of perspective even for street photographers, as it lets you 'get close' to whatever is happening around you without crossing the physical distance.
The example on sale has a number of funky spots on the front element that I can't get off with regular cleaning methods; they seem to be scratches/damaged spots (see the first picture!). They will not affect image quality, but I've reduced the price anyway. Other than this, the lens is in good vintage shape cosmetically, and its mechanically perfect. The glass is clear and the internals are free of oil. The lens comes with the original Canon rear cap (pictured) and an aftermarket front cap (not pictured).