As I understand it's a descent zoom, with some soft corners right? Who cares about corners? I don't, unless it's not just corners, but borders as well.
So how is it? Is it a good match for A7R?
LOL, well, I seriously doubt there will ever be a "final consensus" on the 24-70 f4 lens.
When I recently bought my A7ii, I tried the 24-70mm f4 along with the FE 55mm F1.8 and the FE 28mm F2.8 lenses.
It was obvious that both the primes were far more consistently sharp across the frame, but I ended up keeping the 24-70mm because it was turned out to be much sharper than I had expected (given some of the reviews), and it's a much better fit for my style of shooting, fast and loose.
Many folks here would say it's a shame to buy the A7r and not utilize that exceptional sensor to it's fullest, but I think it mainly comes down to what YOUR needs are.
I needed a one lens solution, and the 24-70 gives me that in a very nice package.
So, if you're a zoom kind of guy, then go ahead and buy the 24-70mm with confidence. It's a fine lens and fun to use.
Another option might be to rent one first and see if it fulfills your needs, either that, or be sure and buy it from some place with a good return policy.