The battery in the HTC 8X isn't the largest you'll come across at a pretty-measly-by-modern-standards 1800mAh. Plus, it's sealed in, so even if you do manage to get your hands on a spare, you'll be able to do no more than look wistfully at it.
At the time of writing this review, even HTC wasn't giving estimates of talk time on its website. So we can't call their claims into question but that's fine since so much power on modern phones is used up through other things that don't involve phone calls anyway.
Our impression of the battery on the HTC Windows Phone 8X is that it's standard HTC fare. Which means that it's OK if you use it frugally, but as soon as you approach anything near real-world use, forget it! The sad thing is that even after all these years, HTC can't make a decent battery.
We took our unit off charge at 8am. We had Wi-Fi on and Bluetooth connected for about 20 mins to the car stereo. We sent about 25 text messages over the course of the day, a handful of emails, took 13 photos, one video and browsed the web for 40 mins or so. By just after 5pm, the battery was down to 10%.
If you turn off all your syncing, you may do better. But the issue here is that this is a phone that is meant to be connected - that's the whole point in Windows Phone.
It's a shame that HTC can't reflect that. There is also a battery saver option which you can engage in times of emergency. But that disables services when the screen is off and makes your email revert to manual fetch. It's functional, but not ideal.
As for connectivity, you have all of the usual suspects here from Wi-Fi a/b/g/n (which explains our fast surf speeds) to Bluetooth and GLONASS GPS.
You've also got NFC support though that doesn't appear to be the most exciting technology right now, but Windows Phone 8 is the first Microsoft OS to support the contactless tech, so it's at least a positive step.