I have to wonder what you are comparing to.
1. The D800 (D800E)? OK, Reasonable. Both 800's are just really big. If you can stand the size... these are actually better options all things considered. The lens options (without all the issues) make this system hard to beat. Admittedly, the size of this system is not ideal. Keep in mind... the A7r does not beat a D800 in image quality.
2. The RX1? Fixed 35mm lens. Great camera and lens. It is just limited.
3. Almost any other camera? Accept lower dynamic range and less resolution and you are fine.
This is all pretty easy stuff to understand.
The A7 and A7r have one fatal flaw for now. There are no ultra-wides that work well except the huge Nikon (with adapter) 14-24. A few other DSLR lenses (with adapters) also come to mind. The Leicas, Zeiss and V RF lenses just have too many color and vignetting issues at the corners to be useful. The Sony 10-18 is "barely useable" but you have to crop before you are done. Messy.
What a difference full frame makes.
While I am ranting... DXO makes the best RAW workflow. It is second to none. I use Photoshop AFTER I do the 1st pass in DXO Optics Pro. If you haven't tried DXO... you need to.
BTW... I like the A7r. But I won't REALLY love it until I have an ultra wide option that is a bit smaller than the 14-24 with an adapter. The camera is terrific. The lens options are not... yet.