The Xperia Z4 follows the same design as its predecessors, which can be a good or a bad thing depending on how you look at it. The squarish shape, metal frame, and glass back are part of the brand's identity, but at the same time they're iterative and have become boring. A few notable outside differences (compared to the Z3) find the speakers pushed to the edge of the top and bottom bezels for a more refined front panel design, the nano SIM combined with the MicroSD in one slot for less ports and cleaner lines on the side of the phone, and finally a cap-less MicroUSB port on the bottom of the device. You won't have to fiddle with it each time you want to charge your device or worry about making sure it's closed before you immerse it. But thankfully, the streamlining didn't affect the dedicated camera button, which keeps it place and makes it possible to take photos and videos underwater without messing with the touchscreen.

At 146 x 72 x 6.9 mm and 144g, the Z4 is the exact same height and width as the Z3, but 0.4mm thinner and 8 grams lighter. That svelter profile seems to have been achieved at the expense of the battery, which is still non-removable but has dropped its capacity from 3100 to 2930mAh.

Under the almost-unchanged hood, you'll find a set of almost-unchanged specs from the Xperia Z3. The display remains a 5.2" 1080 x 1920 pixels Triluminos panel, there are still 3GBs of RAM, the back camera keeps its 20.7 MP resolution with the 1/2.3" sensor capable of shooting 4K video, and there's the same smorgasbord of connectivity options (Wi-Fi a/b/g/n/ac, Bluetooth 4.1, NFC, MHL, HSDPA, et al.) with an enhanced LTE Cat.6 radio.

The more significant differences affect the processor, front camera, and onboard storage. For better or mostly worse, Qualcomm's now infamous 64-bit octacore Snapdragon 810 is powering the Xperia Z4. The front camera has also jumped up from 2.2MP to 5MP with digital stabilization and a wide-angle for all 'dem selfiez aficionados. And like all of 2015's flagships, the Z4 has upgraded its default storage option to 32GB.

Source : http://www.androidpolice.com/2015/04/20/sony-xperia-z4-announced-in-japan-with-snapdragon-810-1080p-5-2-screen-ip68-waterproofing-with-cap-less-usb-port-and-sonys-signature-design/

Nice to see Camera improvements both front and back. Lack of QHD or Bigger screen is rather disappointing as it would be a very nice step up from the incremental steps from Z1 to Z2 to Z3.

A new metal frame design and capless waterproofing is definitely a plus but overall I'm a little disappointed as Sony usually are the highest of top tier specs. UI and software options will seems to be the focus for this new phone plus the obvious hardware upgrades it'll be interesting to see what their Apps team will do with the Snapdragon 810.

I will be getting this when it comes out UNLESS the HTC One M9+ Comes out in the west from China as that seems to offer everything I would like in a 2015 phone but the lack of waterproofing and my admitted fanboyness to Sony phones means I'll probably still get this. Thoughts?

This looks really nice, and my contract does renew soon...

I love Sony's phones these days.

Still happy with my Z1. Looks ok, but I don't see a reason to upgrade.

I have a Z1 but I'm mainly upgrading for the extra GB of RAM, Double the CPU power, camera upgrades, PS4 connectivity, better software options and colour technology. I would've gotten a Z3 but I'm waiting because of the 8 Core CPU.

Not really happy with how slowly Sony makes improvements to their phones. There have been rumors that this will be their last flagship phone, so I'll likely never own an Xperia.

What rumours?

But it is another nice incremental upgrade given how well desinged the previous phones have been. Sony just needs to improve the software, keep the top class battery and improve on marketing

The inclusion of the exposed waterproof USB port is a good step forward, so long as there is still a microSD card port (I haven't read anything one way or the other)

I'm still happy with my Z2 though, got another year before it needs replacing. What I want is USB type C, wireless charging and that microSD card to still be there

Hmm guess its time I get a Z3. Nothing theyve really done makes it seem worth the extra money and this should lower the price on the Z3 a little.

suggest you wait for the global model to announce end of may which probably a better model than this japan version...

http://www.gsmarena.com/sony_xperia_z4_is_not_the_2015_flagship_stay_tuned_this_may-news-11970.php

Ugh glass back is terrible lol. I only just got my z3 anyway so this doesn't affect me too much. I was thinking about waiting to see if they'd announce a new model but it looks like I should be fine with what I have. No caps though would be nice