Putting a 2500mAh battery into a QHD smartphone is almost always going to result in poor battery life overall. Out of the box? Not so much (which is when most battery benchmarks are made). Throw a handful of apps and games on there and it will become quite noticeable that Samsung should have thrown in a higher capacity battery.
To compare, I use the same apps on my Androids as I do on my iPhones. Facebook, Twitter, Snapchat, Bleacher Report, Netflix, Gmail, Clash of Clans, and a few others. Throughout the day with mild use, I found I had to throw my S6 on the charger at least 3 times vs. the one time I had to charge my iPhone 6 at night before bed.
Will your experience differ from mine? Absolutely. Do I feel comfortable going through 3 charge cycles on a phone per day? Not really. Especially if I can't replace the battery. That alone was excuse enough.