Updates:

2015-10-13:

Readers have pointed out some artefacts:

Jaggies in some images
Black dot artefacts in some images

I have looked into the issues and found that the jaggies were caused by demosaic artefacts in Lightroom combined with strong sharpening. I therefore reprocessed the comparison with MFD images using RawTherapee with default sharpening. Default sharpeing in RT may be regarded weak, but it applies similarly to both images.

The black dots artefacts were caused by mainly by me using the local adjustment brush in LR with automasking to lighten up the chapell against the background. In this case I used the radial filter instead giving a similar effect, that made the black dot artefacts go away.

The images affected by this observations have been (hopefully) updated.

I recently bought a Sony A7rII and this is my experience with that system

What did I buy?

The kit I bought was essentially:

A7rII Body
Sony 90/2.8G Macro
Canon 24/3.5 TSE LII
Metabones MB-EF-E-BT4 adapter
Sony LA-EA3 adpter for A-mount lenses

As a late decision I also added the Sony FE 28-70/3.5-5.6 OSS lens, as I wanted a simple FE mount lens for easy shooting. The 24-70/4 lens may have been a natural choice, but I am under the impression that it is not a truly great lens, so I decided to go with the chaeper but still decent "kit lens".

Why did I buy?

That is a good question and there is no real good answer.

I really wanted a mirrorless camera…

The main reason I wanted a mirrorless camera was:

Getting rid of the mirror
Being able to use Canon TSE lenses
Being able to use almost any lens
More than 24 MP resolution
Grass is always greener on the other side of the fence

Why didn't I buy the original A7r?

Looking at the sensor I felt it was old technology. The A7 had a newer sensor with EFSC (Electronic First Shutter Curtain) and on sensor Phase Detecting AF (PDAF). I had some experience with bot on my Sony Alpha 99, and I didn't want a lesser sensor.

Why did I buy the A7rII?

I felt it has improved in some of the areas where the original A7r was lacking. It added PDAF and EFSC. It also had resolution similar to my P45+ back, so I could see that I could travel with a single system instead of two.

What I don't like with the A7rII?

Well, there is a lot to like… But there are some things I feel Sony should fix…

Image stabilisation and AF should be overriden by presets. I want a preset for shooting on tripod and that should disable both image stabilisation and AF.
Battery is to small. Use the same batteries as the Alpha 99!
Please add an option to toggle peaking and zebras.
Zebras optimized for movies. Zebra should indicate real world clipping when shooting stills
Please give us a nice standard zoom with excellent sharpness
Please give us 12.5X magnification in focusing assistance

Initial shooting experience

Original Metabones adapter is broken. doesn't connect to camera. Newer adapter may work -- no observations to the contrary
Most lenses work reasonably well
AF with A-mount lenses is accurate, but somewhat slow
AF with original Sony E-mount lenses very god
Tendency to overexpose

Extended shooting experience

I have been on travel shooting for three weeks since I got the camera. After a few thousands images I have come up with the following observations.

Lenses

I have used the following adapted lenses:

Sigma 10/2.8 APS-C fisheye
Sigma 12-24/4.5-5.6 zoom
Canon 24/3.5 TSE LII
Sony 24-70/2.8 ZA zoom (that has been subject to fall)
Sony 70-300/4.5-5.6G
Sony 70-400/4-5.6G

And also these native mount lenses:

Sony 28-70/3.5-5.6 (kit lens)
Sony 90/2.8 G Macro

What I have found was that both Sigma lenses performed well shooting interiors. Shooting landscape they are usable but are a bit behind image quality. I am a bit more interested in a 16-35/4 zoom than I was before.

The 24-70/2.8 zoom performed very well in the 24-50 mm range. It has never been really good at the long end which is a reason I wanted a 85-90 mm lens of high quality.

Below is a near edge crop shot with that lens at 55 mm and f/11:

With the uncropped image shown here:

The 70-400/4-5.6G served really well. The 70-300/4.5-5.6G I only have used to save weight on some walks. AF was usable.

Here is a near corner crop from the 70-400/4-5.6G:

The full image is shown below:

The 90/2.8G Macro is a great lens, really showing what camera is capable of:

With the full image below:

The Sigma 12-24 I found usable but inconsistent, this a a near edge crop at actual pixels:

From this image.

On the other hand the upperside left crop below is really bad:

Findings on the lens front

The short version of my findings is that I would like to have a high quality 24-70/4 lens from Sony or someone else. The 16-35 lens is on the shopping list. The old Sony lenses are very much usable with the available adapters.

It obviously makes sense to use the Sony with high quality primes, but I feel that zooms give me a needed flexibility for exact framing.

I have been shooting a Hasselblad with a P45+ for some time, using different prime lenses. That obviously worked for me, too. I will look a bit more into complementing my equipment with some primes lenses, but good primes don't come cheap.

Using the A7rII with Canon lenses

One of my main interest with the A7rII was to be able to use Canon's T&S lenses. I bought a Metabones Mark IV adapter and a 24/3.5 TSE LII to be used with the Sony A7rII. My first Metabones quickly developed some unreliability, failing to connect with the camera most of the time. I bought a later version called Mark IVT of the Metabones and that worked mstly with just a few hang ups.

Metabones is working on new firmware releases for the A7rII so some or most of those issues may be resolved.

With the second Metabones I had little problems.

The 24/3.5 TSE LII I have is someowhat limited in sharpness compared to the Sony 24-70/2.8 zoom at 24 mm. May be the sample I have is not that good. I have been shooting quite some architecture kind stuff and the 24/3.5 worked very well on that kind of subjects. Focusing is OK, but could use a bit more focusing throw.

I also had the opportunity to shoot Hans Kruse's 24-70/2.8 and his 100-400/4.5-5.6 zoom on the Metabones. Both lenses worked well, except AF being unusable beyond 200 mm on the 100-400/4.5-5.6 zoom. What happens on the 100-400 at 200 mm is that the lens starts a slow hunt for focus. Once it gets close to optimal focus it snaps into focus. The Sony 70-400/4-5.6G did not have a similar issue.

The Canon 24-70/2.8 LII is a very attractive lens and I may ending up buying it. It is a much nicer design than the Sony 24-70/2.8ZA.

Can the Sony replace the Hasselblad?

I have only shot a few comparison images and it is to early to draw conclusions. What I have seen so far would make me believe that the Sony may keep up with "Blad" with the very best lenses.

Here are two samples comparing the Sony 24-70/2.8 ZA at f/8 to the Distagon 60/3.5 at f/8 with A7rII and P45+

Sony A7rII Central crop: