The more appropriate question would be, "Is there any Zuiko lens that is not good glass?". The 135f3.5 is a tiny little lens, and it is particularly striking as the silver nose. I agree that it is an odd length, but it would probably be very appropriate for portrait photographers.
It is so small that it is easy to keep in the bag "just in case", though. Given that it does not have a significant perspective distortion it is handy for framing distant scenes that you can't physically approach. I got some nice shots of Stonehenge from outside the fence with mine.