I sold a Sony A99 and Alpha mount lens collection to purchase a Sony a7II. The primary reason for the switch was to have a full-frame camera on which I could use the same set of legacy lenses that I use on my Olympus OMD E-5M. Both cameras have in-body image stabilization, which is a wonderful feature to have when using legacy glass.
So far, the a7II is fulfilling its intended purpose nicely. I really like the user interface. I have big hands and the camera, while much smaller than the a99, might actually be easier to use due to an excellent layout and extensive customization capabilities that put all the features needed for manual focus shooting at your fingertips. The focus peaking and image magnification features of the electronic viewfinder (EVF) make it very easy to nail the focus manually.
The a7II lacks the speed of the a99, both in terms of frame rate and general responsiveness, so this is probably not the camera for a dedicated sports photographer. It also lacks some of the more important frills of the a99, such as dual memory cards and GPS.
The biggest gripe I have is that the whites in the viewfinder are too dim in bright sunlight (they are fine in other scenes), leading to the temptation to dial in exposure compensation until they look right. Use of zebras or monitoring the histogram in the viewfinder are necessary to determine proper exposure in bright sunlight.
The battery life isn't great, but the small batteries are cheap, so this is not a big deal.
One idiosyncrasy is that when auto ISO is selected, the camera defaults to 1/60 sec whenever possible, regardless of the focal length used, unless you are in shutter priority mode.
Overall, I'm happy, but if I were going to buy a camera primarily for use with autofocus lenses, I would buy an a99, especially at the current price point.