I am into landscape and wildlife (bird) photography. I am not a pro, but I sell stock photographs online through different microstock agencies. These agencies demand photographs of professional standard. The 7D2 is an additional new tool in my camera arsenal. I haven't tried the video of the 7D2 yet. My opinion is based upon my observations in the field.
I used to own the original 7D, then I moved on to the 1DIV and now the 1DX. Needless to say, the 1DX is a fantastic camera. Pro body with pro quality result. At $6,800 (when it was released), you expect the best of everything. It delivers. With lots of experience in using the 1DX, I can say that the 7D2 is no slouch. I purchased the 7D2 for extra reach due to its 1.6x crop factor.
In terms of AF accuracy and speed, the 7D2 beats the old 7D, the 1DIV, and is almost the equal to the 1DX. The 1DX's shutter responsiveness is a bit faster than the 7D2 (no big deal here), and the AF lock-on is tighter. I guess the 1DX's huge battery may be the big contributor to the super tight AF. However, the 7D2 is not far behind at all. Another bonus is that the shutter is way quieter than the 1DX. Quieter shutter release is good for wildlife photography as you don't want to let the birds know you are present.
Last week, I used the 7D2 and the 500mm f/4 IS II combo. The 500 mm becomes 800 mm because of the 1.6x crop factor of the 7D2. With good lighting, AF is super quick and the photos are tack sharp. I have been using the 1DX + 1.4x III + 500 mm f/4 IS II to get to 700mm. I got tack sharp photos as well. However, the 7D2 and the 500mm yields even sharper photos. The 1.4x III does degrade the pictures by, I would say, 10% to 15%. The 2X III degrades by 20% to 25% in my opinion. I always reserve the 2X III for static subjects. 1.4X III can be used effectively for Bird in Flight. I really like the extra reach of the 7D2. Now I can get 800mm with the 7D2 and the 500mm combo without the 1.4X III extender. That is why the photos are a bit sharper. The 7D2 has 20 mp vs the 1DX's 18 mp. The extra 2 mp is no big deal, but it does allow a tighter cropping.
What are the downsides of the 7D2? Well, I mentioned good lighting above. The 7D2 is impressive with good lighting. With low light or less ideal lighting, the 1DX excels. The 7D2 becomes a bit slower. The biggest gripe I have with the 7D2 is its noise control, which is only slightly better (perhaps 2/3 of a stop) than the 7D and not as good as the 1DIV. But keep in mind that the IDIV has only 16 mp and it is 1.3x crop, meaning bigger sensor. Darker/shadow areas show more prominent noise with the 7D2. The 1DX's noise control is the best. Full frame sensor is way better with noise than a crop sensor. I always blow up my raw photos to 100% to check for noise and sharpness. All the stock agencies do the same. I really wish Canon did better with the 7D2's noise control. Post-processing can reduce the 7D2's noise to a level for commercial use. Without looking at the photos at 100%, the 7D2 files look clean. So far I only tried ISO 500 and 640 with the 7D2. The key is to nail your exposure with the 7D2. You have more wiggle room with the 1DX though. In other words, you need to work harder to get the best results from the 7D2. Also, its battery life is short. I could only shoot approx. 900 photos before I need to change the battery and I didn't use video at all.
I will use the 1DX for ISO 1250 and above. When I use the 7D2, I will try to keep it at ISO 1000 or less. For commerical use, I have to keep the noise level really low. Another observation is that crop sensor does yield more depth of field than a full frame sensor. It seems f/5.6 with the 7D2 is like f/7.1 or even f/8 with the 1DX. I can actually use more wide open f/stops and thus lower ISO with the 7D2.
Overall, the 7D2 is an excellent camera for wildlife and sport photography. Excellent AF, speed, and sharpness is the admission ticket to high quality wildlife photos. By now you probably are thinking that the 1DX is still the best. Yes it is. But the 7D2 at $1,800 (which is 1/3 of the 1DX) is the real deal. I can comfortably use it to produce photographs for commercial use. Think about it. The 7D2 is 20 mp (2 mp more than the 7D) and its noise level is about 2/3 stop better than the 7D. Plus it has better AF system and its LCD screen has higher resolution than the 1DX. To me, these are good improvements. The 7D2 is awesome. Below are some sample images I took with the 7D2 and the 500 mm f/4 IS II combo. Details and sharpness are incredible.