yes 70-200mm f/4 IS sharpness across focal length and aperture is legendary.
the size and weight is also very good for walk around. AF speed is very fast. IS make some noise when activated, but you can always turn it off when you don't need it.
One of the best lens Canon produces, it is almost perfect!
The only imperfection i find is it is not ideal shooting moving objects
in low light condition. Second, the bokeh
is not as easy to achieve/better comparing to f/2.8 version.
But the f/2.8 IS version is $600 different and bigger in size/weight
The other consideration is f/2.8, without IS actually i have lil bit regret not buying this lens instead of f4 IS in the first place (because kind of photography i'm involved with is more of action and portrait).
While, the f4 IS is more about general purposes. It can do many things
and deliver excellent result, but not as best as f/2.8 version in certain
condition such as sports and portraiture.
But as your first L lens you will have (like me at that time) you'll be very satisfied.
One dumb question: Is a 70-200mm F4L shot cropped, better quality that the equivalent 70-300mm un-cropped shot?
it will be better, but u lose image resolution, if you have 12 megapixel or greater i think it won't be a problem for not so big print.