I've had one for 3 weeks, and I have to say the novelty of a new shiny wore off sooner than I'd hoped. The device is very capable, and is a big step up from my Galaxy SII.
Pros
Sony launcher is nice, although I've gone back to Apex.
Camera is very good in good light
Can take a 64Gb SD card
Battery lasts for ages with mild to moderate use
Stamina mode comes in handy if you want to eek more out of your battery when you're getting low
Waterproof which is handy when you have a 14 month old who wants to get everything covered in food and water
Cons
Camera is awful in low light
Mic is a little quiet
Screen isn't as vivid as my S II was
My options were HTC One, Lumia 1020 or Z1. I settled on the Z1 as it has a higher spec in terms of CPU and RAM than the other 2.