Thing is mate, you're effectively running a low-power computer/laptop off-of a battery that fits inside a phone.. people who go on about how their nokia 100 lasted for 2 weeks on a good charge are daft..
Phones now have full colour well-lit displays, various radio antenna's (5+) wifi, bluetooth, NFC, etc etc etc
They leave it on all day and expect the thing to also last through a gaming session on something like Anomoly 2 etc.. it's just daft to expect it to last that long..
Good example, I had an iPhone 4s 2 phones ago. It wouldn't last the day under usual usage scenario, which is fine because I used it a lot..
Once I retired it, I put it into airplane mode, turned BT off and dimmed the display down as far as it would go, and basically turned off all the antenna's and wireless stuff that I could... and used it as an alarm and I shit you not, it lasted an entire week and a half on a single charge... in standby almost the whole time.
It's all about how you use the device and what you're prepared to do to keep it alive. If you really are a heavy user, by a recharge pack/bigger battery