3430 mAh battery, 5.5" 4K IPS screen, SD810 ... this is NOT going to last "power users" for 2 days. So they're saying something to the effect of users getting between 5 and 10 hours of usage in a 40 to 48 hour period. The "power users", depending on all the typical conditions, should probably expect 5 to 9 hours of SOT in a typical high usage day.
Here is their statement on battery: ****Battery life has been measured against Sony Mobile Communications AB’s smartphone usage profile, defined in September 2014 to represent the typical smartphone user’s active condition, including but not limited to a range of usage scenarios (calling, texting, web browsing, social networking, game playing, music listening, picture taking, picture browsing, online video watching, video recording and playback).
Now, the September 2014 AVERAGE user... here's what they say about that: Typical Smartphone User usage profile. This involved using the device for approximately 5 hours in a 24-hour period, for a range of typical usage scenarios (calling, texting, web, social networking, games, camera, music and video).
For context, the Moto X 2013 with a 4.7" 720p AMOLED screen and SD600[SUB]/2[/SUB] lasted the average user between 20 and 24 hours and average SOT was between 3 and 4 hours.
OF COURSE I am speculating, I don't have this device and haven't seen any serious reviews - this is based on analyzing their statements, what we know of the specs and what we know about how batteries actually function under load. The biggest two drivers of batteries suffering are typically poor idle (Apple has this fairly well under control) and the screen's power draw. If Sony has these two things under control (I assume they're most of the way there if they're making these claims) - then we can expect VERY solid battery life. But let's also be reasonable about what to expect. I'd hate to see people expect to get 10+ hours of SOT over a 24-48 hour period and then rage against the device because it's not there yet.