Mini review of mine
It arrived on Friday to replace my Xperia S.
first impressions are very good. It's basically a slightly slimmer, slightly lighter version of the S - with a bigger and brighter screen. Build quality is very good - the rear cover isn't sparkly like some of the pics show, it's a matt black and quite soft, think the Sony X10 here. It works well IMO.
Camera is brilliant - very fast to respond too. Daytime pics on par with the Xperia S when you just use the phone screen to view, but there must be some difference with the compression or such on them, as when transferred to a desktop PC or such the difference is noticable. Low light pics come out much better now thanks to a better LED flash.
Speed overall is fantastic. It's sharper and faster than the Xperia S, not that the S was slow by any means. Lots of flack in some forums and so on about it not being a quad core... it doesn't NEED to be a quad core, it's a fast dual core and it works very well.
Battery life is decent, no issues getting through a whole day with wifi enabled, and bluetooth used in the car. Charge overnight, good to go again. Similar to my experience with the S really.
Speaker phone is better than the S - likely due to better 'speakers' in the unit itself. Not tried using it for music yet so can't report on that.
Lack of JB is annoying, I admit that, I have been annoyed at EVERY Sony phone I've owned for a similar reason. I just hope the update comes quickly, however, out of the box it runs very quickly and has everything I'd want - lack of JB annoys me purely because, like you lot, I like to tweak, I like to have the latest tech etc etc - I can't see it bothering joe public.
Marketing - as it's the 'bond phone' - i.e. in the new skyfall film, I guess it'll sell well enough for Sony to continue to produce these.