Way back when, I loved Sony for audio, and then, they became very, very average. More recently, they bought Minolta's camera division, a very, very average group in its own right, and they improved upon it with better technology.
I was not a fan, but I was glad to see a third camera maker with a fat wallet. Canon had become slow and fat, and might as well be named Compromise (especially with anything under US$3000), and Nikon was returning to the fight but seemed to have manufacturing issues at important times.
When I was selling SLRs way back when, Minolta was a safe choice. It wasn't good but it wasn't bad. In 135 Format, Nikon, Olympus, and Pentax were good with Minolta a step below them and Canon wasn't even a factor.
Sony's A7 came at a critical time. The company was bleeding money and needed some success, any success. There were so many people chanting "Full Frame Full Frame" as if it was some panacea, that Sony took advantage of the situation and created a 135 Format-sized sensor with box of electronics around it. The reviews weren't overly optimistic. While the image quality was very good, the operational characteristics were bad. At least, they were serious about lenses, attention their NEX-system wasn't getting.
The A7 Mk II has fixed a lot of that, apparently, according to early reports I've seen. I'm actually thinking about what it could do for me because I'm in love with the idea of it, even if the execution isn't amazing.
They have increased the responsiveness and given the sensor 5-axis image stabilization, so that every lens will be stabilized--not at easy feat given the size of the sensor. If it works as well as Olympus' 5-axis image stabilization, I'd be happy.
You can bet that they've looked at every review of the A7 and put attention to every negative comment. The grip and overall handling didn't suit me, and it seems that they've been busy. I wish that all mirror-less camera makers would consider the battery size more important. Panasonic is pretty much the only company that has, with the GH3 and GH4, because of video recording. It works well.
Just this past Friday and Saturday, I was photographing a scooter competition in a huge indoor skate park. ISO 3200 was necessary. That is the maximum sensitivity I will use and keep photos. The GH4 video looked better than the E-M1's photos at that sensitivity but then, 1080p video doesn't cover as much area. Still, I was thinking that a Nikon D750 or this A7 Mk II would take care of the problem much better.
The D750 would likely be a whole lot more responsive. The Expeed 4 processor would probably be better at clean images, given that it has been used on the highest end bodies. The A7 Mk II (and most mirror-less models) seems more for anything but sports. The E-M1 and GH4 are very responsive, but there are times when they seem to be thinking instead of doing.
As I've been thinking, the improvements make the Sony A7 MK II a good start. In two more generations, it should be a great body.
Update 2015.11.04: After reading this DPReview article about the A7R Mk II, it shows that others are finding Sony to be providing great technology but not great cameras. Since I shoot sports mainly, it spoke to me about the chances of getting photos that don't wait for you.
Update 2015.11.17: I mentioned photographing a scooter competition indoors. I went back to the same indoor skate park in August. I used the Nikon D7200 in ISO 51,200 Black & White mode, along with the Panasonic GH4. I tried using the Nikon D7200 at typical ISO sensitivities and it was selecting ISO 14,400 while the GH4 was selecting ISO 200 to 400. Sure, the image quality wasn't as great as it would have been with a 135 Format-sized sensor but getting the shots was important. Waiting for a camera that doesn't respond would be frustrating.
The use of lossy compression was a bad move, no matter how big the raw files were. How can you claim to have a file which contains all of the information, if things are missing?