It is far too soft. Look at www.birdpix.nl to see what enthusiasts expect in terms of IQ and composition. I had the same trouble with the 7D + 100-400mm L - 50% of my photos were rejected by birdpix as being too soft and/or noisy. Since upgrading to the 5D III and 300mm f/2.8 + 2xTC, the IQ of my shots has improved so dramatically so that most photos are acceptable. If you can't afford that gear, the Canon SX50 also does much better than the 7D + 100-400mm for static subjects.
Ya that is something I have been noticing; that the 100-400 just isn't that sharp unless you are very close. I have some shots with the lens that you can see each individual hair on an owl, but not many. This shot is as focused as sharp as can be for this lens as verified by 200% view. I think being closer would have captured more detail.
I am not sure I can justify the cost of a canon great white like the 300 2.8 at this time as I am preparing to buy a new condo. Do you think a 400 5.6 would be sharper than the 100-400? Or are better results possible with the 100-400 with better technique?
I agree with alan, the image is pretty soft. Notorious problem with the 100-400. That said, I would try to fine tune AFMA for that lens on that body before you buy something new. I had serious softness problems with my copy on a 7D, but using Reikan FoCal, I eventually ended up with s -12 AFMA that made it a lot sharper. Still not as sharp as a 300/2.8 or 600/4, but definitely much sharper than it was originally. Could save you a lot of money.
Another option, if you really want maximum sharpness for a great price, is the EF 300mm f/4 L IS. Not as sharp as the EF 300mm f/2.8 L IS II, but sharper than the 100-400 even w/ AFMA, and FAR lighter than the 300/2,8. It works with the 1.4x TC for a 420/5.6 in case you need some extra reach and have good light.
One of the most important things in bird photography, more so than composition IMO, is head angle. You want the bird to engage the viewer...do a HA where the bill is 3-4 degrees inward towards the viewer tends to be best. Parallel to the sensor is ok, too. More than 5-7 degrees, and your getting into more specialized territory...it can work, but often not as well as a slighter angle. Any angle outward, away from the viewer, and the photo quickly loses its appeal, with a few exceptions (i.e a parent feeding a chick, where the parent may be facing slightly away.)
Once you get HA down, then worry about composition.
BTW, I should note that the HA in your posted photo is a good example of GOOD HA...so keep striving for that. I think as long as HA is good, explicitly following the "rules" of composition is less important (especially since they are guidelines, not rules, in the first place.)