Just about every device since late 2013 seems to be able to get most users through a normal day without issue. The exceptions are rare (some S6 users, knockoff phones, etc). I'd be pretty floored if this was worse than the 2014 X given that the battery is much huger and the processor is better, etc. It is hilarious to see commentary about a 3k mAh battery being "small". That battery is ENORMOUS for a phone. Yes, there have been bigger - but the Note 5 has the same 3k mAh battery and has better battery life than the Note 4 - which had a larger battery.
mAh does NOT equate to battery life. Battery life equates to battery life. The list of factors that influence battery life is very long and depends mostly on factors that have nothing to do with the phone itself - the main drivers of poor battery life are the environment and the user. In short, the processor, screen tech and usage have FAR more influence on battery life than the size of the battery itself.
"Actual battery performance will vary and depends on many factors including signal strength, network configuration, age of battery, operating temperature, features selected, device settings, and voice, data, and other application usage patterns".