I must admit I like my 135mm lenses, especially the f3.5s. Why? Because they are small, light and real fun to get to the details of my subject. These lenses are usually so light you hardly notice the extra weight on the camera and you can carry them around all day. The above image was taken with the Olympus OM 135 f3.5 which is quite a good lens. My other 135mm lenses incluse a Pentax, Nikon, Konica and Minolta. What does spoil it somewhat is the adapter required to use the lens which does add to the overall length of the lens. In some cases it nearly adds 40% to the length, which isn't ideal but is the price you pay for using these lenses on modern digital cameras.
Some of these lenses are easier to use than others and the Olympus is one of the easier ones. If you use these lenses wide open then more care must be taken when focusing. It's even harder with the f2.8 versions which also adds some weight to the whole rig. Of course, the longer the focal length the harder it is to use. Blurry images is also possible because there is no image stabilisation with these older lenses and the Sony bodies doesn't have IBIS. The Olympus M43 bodies are a diffeent story however, and I must say, I have become a big fan of this great function. The Panasonic GX7 also has IBIS and I take my hat off to Panasonic for implementing this feature in their latest camera.