I did a ton of research into these when I was shopping for cameras. From what I read, the huge megapixel amount is both good and bad. On the plus side, you can shoot in a LOT lower light, because you can't even see the ISO effect on the pixels after you resize. On the negative side, that can make you lazy, because you don't really need to have everything perfect since you're not likely going to be blowing it up to billboard size.

I ended up deciding on getting the older alpha a7 II, and then waiting for a future release, since I didn't feel like I really needed the upgrade, and it was a lot more in price. Still haven't gotten it though, since that was right before the crash, so waiting for crypto to return.