8 out of 10 points and recommendedOffcourse all the nice things you can do with a tilt/shift lens. 45 mm is nice on a FF camera. Very good build.I do not like the bokeh, the only con I can think off.
The possibility's are enormous if you know how to use the lens, it is not so very easy to learn. I like the 45 mm on a FF very much, just in the middle of my two favourite's , the 35 mm and the 50/55 mm. It is easy to create miniature with this lens. Portraits also nice, but you will not use that very often. Canon says that it is not possible to use extenders, that is not true. I do not know why they say that. Just as my TS-E24 mm mark II (wich has a much higher IQ) I use the shift the most. Buildings and so on. I very much like the build quality, it is just like a very good L lens. No autofocus is no issue for me. Good IQ but no stellar. Bokeh is ugly, so be careful with trees in the background. That also means you can not really use the lens as an all-round lens. There are better 50 mm around with much nicer bokeh and even zooms can do better.reviewed November 3rd, 2011 (purchased for $1,174)
8 out of 10 points and recommendedLight, build-in hood, very nice IQ, nice Bokeh, cheap, 800 euro for a second handNo IS, F5.6 with extenders makes it F8.0
Never liked the EF 300 MM F4.0, the EF 100-400 mm was already better. But the 400 MM F5.6L surprised me. The IQ is very very good. For a short time I have had the EF 400 F2.8 ISL. The IQ of that lens is out of this world, as is the weight. You need a truck to get where you want to take your photo's. That is for professionals in sport or for bird watchers standing in one place whole day. That is not my cup of tea.reviewed September 10th, 2012 (purchased for $1,000)
I bought this lens and took it out for a walk in the park. With a monopod. I could walked for hours, the lens is light. Much lighter then the 100-400, but you can walk around with that zoom. I set my 5D mark II on autoiso, something I normally do not do. Always on AV. But the camera did not go under 1/320 second and you need that fast shutter time. I tried a couple of photo's without the monopod and it goes very well with auto iso with a some misses. Hand held makes you very very aware of the shutter time.
But coming home and seeing the results, WOW! The 300 F4.0 and the 100-400 mm never gave me a WoW effect, this lens does. I do have to get used working without IS, but with a monopod you are flexibel and with a tripod you have a super lens.