Canon EF 135mm f/2 L
Feature Highlights
Lens f-stop range is f/2.0 to f/32 and lens does not rotate when focusing.
Filter size is 72mm, Minimum Focus Distance is 0.9 meters, View Angle is 18 degrees.


User Rating is 9.9 (out of 10) with over 360 total reviews.

Pros:
The number one most loved feature is the beautiful creamy bokeh behind your subject.  
The f/2 is very usable when doing street photos and full body shots of models.  The
number two favorite aspect of this lens is the extremely Sharp photos and beautiful Colors.
 The number three comment is the fast quiet motor for very fast focusing.


Cons:
The only complaints listed have nothing to do with photo quality.  One is people want IS
(image stabilizer) features.  The other complaint is very hard to use on smaller crop body
1.6x cameras.  There were also a few comments that are common for most prime lens
about not being able to zoom to frame your shot.


Usage:
The most common listed use for this lens is portraits and street photos.

Conclusion:
If you enjoy the great photos that a prime lens can give you and need something that gives
you a creamy bokeh, this is the perfect lens.  This lens is the only prime "L" series lens
that cost under $1,000 USD.  If you do not mind using your legs to zoom this lens in and
out, this is the perfect lens for many uses.


Source:
Fred Miranda Product Review