Here's my mini review
I'll try to sum up my experience so far.
THE GOOD
This phone looks phenomenally good. I love the monolithic design and the all black exterior. The absence of ports (or them being covered with flaps) makes the phone look very sleek. The power button placement is the best I've come across so far, I wonder how no one else has come to the idea to place it there.

The overall build quality is great, much better than the S3 I had before this phone, although the S3 was put together very well and had no big problems in that department.
The performance of the phone is absolutely staggering. I tried torturing the phone to find its flaws in the software and failed miserably. It works effortlessly, the 2 GB of RAM really shows and makes multitasking a breeze.
The HD resolution is fantastic, I really strained to see individual pixels on the screen but my shoddy eyes can't discern them.

makes watching HD video (with BRAVIA) a real joy. There are gripes about the screen, yes, more of that in THE BAD section below.
I find the UI reasonably okay, I love the Walkman lockscreen widget. While I'm talking about Walkman, I have to commend the sound quality of the phone and the adjustments that can be made in that department. Makes using the phone as a media centre in my car a joy. Also, the supplied headset is absolutely fabulous, great sound (once you manage to fit it in your ears, though).
THE BAD
The screen. Maybe it's just my unit, but the colors are nowhere near the AMOLED screen on the S3 which has great, rich (over)saturated colours and great blacks. Not that big a deal for me, maybe once we (maybe) get the screen calibration app we will be able to manage the picture. And yes, viewing angles are not that good. BUT - it's not as bright as the S3's AMOLED which made watching Family Guy in bed last night in a pitch black room a joy for my eyes.
The all glass surface of the phone is a massive fingerprint magnet, within 20 minutes of unpacking it my phone already looked as if it came from a muddy trench
The protective flaps on the phone's body will be a massive nuisance to some people, I personally don't mind (a small price to pay for having a waterproof phone).
The vibration motor is... weird. Makes a weird sound when typing fast when it winds up. The camera takes a bit too long to open.
Compared to the S3, wifi range is smaller. At the same place (my garage) I got 1-2 bars of wifi with the S3, no reception with the Z.
My LED notifications don't work. I will reset the phone later today and see if it fixes things.
The feeble speaker is the biggest dissapointment. No, wait, it isn't. The speaker placement is.

it is really hard to hold the phone without covering it.
THE UNKNOWN
Battery life is still a mystery to me, charged it fully the first time last night, gonna give it a couple of full cycles. Also, haven't had the time to try Stamina mode.
This is it so far, will update with more info.