I have to say that so far, after nearly two months with the Sony A7 'buyers remorse' has yet to set in. Not even a twinge of regret. In fact, the more I use the camera, the more I like it.
I know this is an entirely personal opinion but here, for me are the key features:
1. Outstanding sensor and picture quality: quite simply the best digital sensor I have tried yet. Prior to owning the A7 (and the RX1 before it) I did not believe that a digital sensor could capture the dynamic range that occurs between lands and sky in landscape photographs but the Sony 24mpx sensor does that. What is more, I am convinced that the sensor outshines the lens and actually contributes positively to the results. Prior to this the biggest challenge to me in digital sensors was matching the optical quality of the lens.
2. A form factor that is user friendly: I have never understood the desire by camera manufacturers to create a product which is the camera equivalent of a laptop computer. I have always wanted a 'netbook' or 'tablet' equivalent. Now I have it. It may not be important to you but I literally tramp miles around London streets and the smaller, lighter package means lower weight, or more lenses. A much better choice (for me).
3. Manual focussing that works: I have always been highly sceptical about focussing manual lenses on any digital camera, except my now long gone Leica M8, which when you think about it comes with a manual lens 'assist' in the form of the range-finder patch. I hooted at the use of manual lenses on m43rds cameras because frankly the CV range offered little in iq advantage over the PanaLeica equivalents and they were (of course) AF. Well, blow me down but manual focussing with the A7 is a snap. I never would have believed it. And in fact I did not until I tried it in the camera shop, and in disbelief at how good it was I immediately plunked down my credit card on the A7 and a CV 21/1.8.
4. A body for all reasons: it took me a few weeks to really see the beauty of a digital body which is a platform for any lenses. Within two weeks I bought back into Leica for the reasons stated in point 3. I am beginning to wonder if I was a tad previous at selling my Hasselblad lenses.
5. Articulating screen: why oh why it took so long for professional cameras to have an articulating screen is beyond me. I suppose that originally they looked like a consumer-type feature. Well done to Sony for incorporating them so early in the product line. I rarely use it but it is a great feature with wide angle lenses, which cry out to be shot down and dirty.
6. You mean it is an EVF? I won't even dignify any complaints about the EVF. My belief is that in a few years people will look back on OVFs and mirrors the same way we do now on film cameras. Quaint solution to a problem in the analogue world but completely out of date in the modern digital world. What you see is what you get - what could possibly be a problem with that? Well done Sony, again.
I could probably think of some more reasons but at this point in time I am happy bunny with the A7 and while it may not have the soul of Leica rangefinder or the charm of a MF body, in practical use it beats them into the ground, as far as I am concerned.
Just my two cents