Quick note. The review says: "Event shooters may like the extra 2/3rds of a stop of light over the 70-200 f/2.8" f/2 is one full stop away from f/2.8
The 135mm f/2 L is a fine lens. I've had a copy for several years. It is especially useful when you need to shoot a longer FL wide open and can tolerate the very narrow DOF.
However... once I got the 70-200mm f/2.8 L IS II it turned out that I barely used this lens anymore. Yes, f/2.8 is not as large as f/2 and yes, the zoom is a lot bigger. However, f/2.8 does produce pretty nice DOF, too, the IS extends the low light range of the zoom, and the flexibility of the zoom is quite useful.
For those who are sure they want a prime at this FL, the 135 f/2 is certainly a fine one. However, such lenses seem to become more and more specialized things these days.