Only said expected release in Japan this summer. My guess would be released in Europe sometime in the fall. North America? Who knows if we'll even see it.
It certainly looks like a very mild update to the Z3 but if someone values expandable memory and wants a waterprood device, this is certainly an option. The camera is pretty good and the last few Xperia Z models have shown very good battery performance, although like he S6, this model has a smaller battery compared to its predecessor thanks to Sony slimming it down even further. Supposedly it will have a waterproof USB port so no pain in the ass flap to deal with.