After some trial and error with the Canon 135L, I have come to conclusion for my needs the lens is well suited for activities closer to home. For outdoor pictures of Christina and dogs, the 135L is great - especially at golden hour when the background is chock full of warm colors. For indoor work under strobes such as product shots, the 135L is excellent. I would even go so far as saying the 135L is good for indoor portraits - provided there is ample working distance. And most likely some fill flash will be needed in order to achieve acceptable shutter speeds.

When vacationing or traveling, it is unlikely I would bring the 135L. If there was extra room available in the camera bag, I might bring the 135L “just in case”. When traveling I prefer a 90 or 100mm focal length for the portraits & candids because the added field view which provides a better sense of context / location. This is simply my preference and no a strike against the 135L per-se. Some other observations regarding the 135L after several years of use:

1. •The rendering is the standard Canon look - moderate saturation, good contrast (not too heavy), a compressed, flat perspective (not much 3D). The high points are sharpness and bokeh. Not much micro-contrast compared to the Contax 100mm Planar.
   

2. •The 135L can double as a pseudo 200mm F2.8 lens when paired with 1.4x II extender. There are some minor trade-offs including added length, increased weight, increased distortion, any anomalies in the bokeh (color fringing, etc) are magnified and exaggerated, slightly slower auto focus performance and a slightly dimmer viewfinder.
   

3. •The 135L feels sharper at F2 than the 200L F2.8 USM II does at F2.8. Based on optical performance alone, I prefer the 135L over the Canon 200mm F2.8 L II.
   

4. •Flare, ghosting, color fringing, chromatic aberrations (CA), etc. are not a problem. The bokeh can have some color fringing, but that is par for just about about every lens made.
   

CONCLUSION

The biggest consideration in buying a 135mm lens is deciding whether or not the 135mm FOV is a good match. People often consider the 135L and 85L as equal options, but the field of view of the two lenses is quite different.

I have owned the Canon 70-200 F2.8 IS and was disappointed in its performance, especially at 200mm. Overall the zoom seemed soft and lacking resolution. After trying several copies of the F2.8 L IS and a couple non-IS 70-200/2.8 L, on an impulse I purchased a 70-200/4 L IS. The 70-200/4 L IS has very good performance at 200mm (compared to the F2.8 zooms) and has become one of my preferred travel lenses.

The 70-200/4 L IS is quite sharp, etc., but it lacks in bokeh and often has too much DOF when trying to isolate a subject from the background. When using the 70-200/4 L IS at home, F4 is often to slow for taking the dog pictures - especially if dogs are running or playing.

I do not use the 135L as often as I should or could. Forthcoming cameras such as the Canon 1D Mark IV are re-writing the rules with the promise of ISO 102,400. I doubt the file quality will be anywhere near acceptable at ISO 102,400, but presumably ISO 6400, 12800 and 25,600 could be quite usable and that is a couple stops faster than ISO 1600 on the 1Ds Mark III. Being able to use the 135L even after the sun sets could be quite interesting - especially city street shots and such where the specular highlights blend very nicely with the 135L’s bokeh.

Optically the 135L is deserving of all the compliments and accolades. The burden is on the photographer to find the right time and place for the lens. If 135mm fits your taste and shooting style, then Canon 135mm L merits consideration. The sharp images and smooth bokeh always bring a smile to my face.