I have a Z1 and love it. I think it is a great phone, the best in its class.
However, I don't see the constant need for small incremental upgrades, and I will have this one until it dies of old age or by the hand of its enemies (my kids).
I certainly don't care for 4K or a megapixel more or less.

But when I do buy a new one, it probably will not be Sony. It definitely won't be Apple or Samsung. Today you can get a cheap Chinese clone for a quarter of the price. Those might be a bit worse, but as long as they run simple utility apps (banking, parking, youtube...) they are good enough. My wife just got one for €100 and it is definitely acceptable and fully functional.

I work for t mobile and they carrief the z, z1, and z3.... Unfortunately they launch their products half a year behind announcement... And the competition surpasses them in the u.s.... Z launched behind s4, z1 behind g2, and z3 behind note 4/i6

Also the z series in the u.s was marketed very badly and the z3 had a lot of issues in the u.s, so bad that t mobile dropped the phone a couple months after launch...... Sony has no presence in the smartphone market anymore in the u.s..... And t mobile said they don't care to carry the z5...... It sucks because on paper the z5 is prob the best phone..... But my own co workers who work at a very high volume store.... Along with other stores have lost any trust if any was there for the z brand from sony.... They relate xperia to trash at t mobile , and it is unfortunate

Other way around. The Z4 in Japan ended up JUST getting localized to the US recently as the Z3+. Except, by "localized to the US" I mean "localized to the UK." In the US you can't get the Z4/3+ yet, you have to wait for the Verizon model of the phone, the Z4v. Which, now, is outdated the moment it actually launches because Sony is awful at launch lag. I'm sitting here on my original Z still because T-mobile pulled the later Z line because of defects, and because I can't personally afford $650 up front on a phone because college. And now that T-Mobile isn't carrying the Z5 I have to hope they'll release worldwide in a timely manner and hopefully that Verizon takes up the Z5. Otherwise I have to switch to a worse phone eventually because Sony doesn't want my money. 

They also laugh at 20 mp.... Because they compared their 8 mp iPhone 5s camera with the z1 20 mp and received way better results...... It's this basic and simple comparison that he general public does and makes them go to another device....

I wish I could buy the Z5 Premium but I don't want a downgrade to my Note 3.

These Xperia phones were on my sight for quite a while. I do use a quite old Samsung Galaxy S, which I like. I plan on getting an Xperia once I can afford it, maybe a secondhand or an older model.

That is because Sony continues to fail to put together the whole package. They have their own network, and one of the largest gaming catalogues in the world, but they are not using them. The Xperia phones are lacking full fuction of Sony's most popular consumer brand, and the PlayStation Vita is missing vital functions that Xperia team is developing for the phones. Sony is workng against itself, and it is hurting them from every angle.

Vita fails because it is not a mobile device (Lacks 4G, cellular communication, and apps), which in turn makes people less inclined to buy one. With a smaller userbase, game sales suffer, and Sony and other publishers can't make money selling games on the platform. If Vita had the ability to replace your smartphone it would be doing much better, and it would be getting many of the same e-reader apps, banking apps, and fitness apps you see on mobile.

Right now Sony has a mobile phone brand that does not take advantage of everything at Sony, and they have a mobile games unit that is in the same boat. They need to merge the two, and put out Sony mobile devices that take full advantage of all of Sony's resources. Once they do that, and break away from the me too OS, then they can start to gain marketshare in the mobile space.

4k is over kill. that Z5 compact looks to be mine once i am done with my Z1 compact though!

Why would he?

4K takes more battery life with little benefit on mobile devices....

YAY?