Received my D750, plus a load of other goodies, earlier this week and it doesn't seem to be displaying the flare issue. To be fair, I'd put the order through about 6 weeks ago and wasn't aware if the issue until a mate pointed it out.
Anyway, WHAT A CAMERA!!! I've been using D7000s for a few years but I needed more detail for product catalogue shooting, and a more responsive video function. I didn't want to go D800 and the D4 was just too pricey for our purchasing dept. at work.
Handling is good, although the button configuration is slightly different to the D7000 if I remember rightly. The front control dial doesn't stand proud enough out from the body for use with cold fingers - I found this yesterday while out on a shoot - and the rear D-pad is a bit spongy compared to my old bodies. The grip hasn't arrived yet, so that will undoubtedly improve handling, because it's quite a small camera for my massive hands...
... However, the image quality is amazing. .NEF files are very different in LR5 compared to my other Nikons and they can take a hell of a lot of adjustment, really flexible files. Detail is superb. High ISO is proper - being able to shoot indoors in dim light is a joy fir getting pics of the kids when I get home from work without relying on flash.
Early days with it and it's certainly a joy to use with good glass - 17-35, 24-70 and 70-200 - and I think that the accompanying D7100 I also got delivered might not get much of a look-in while there's still the novelty of FX goodness