Considering you got your s6 last Friday, are you still messing around with it more than you would normally use your old phone? I know I still would be, it took me a good week to really put my down my s4 when I first got it (but I admit I had much more free time back then). Also the battery itself is smaller in capacity compared to the s5.
Many of the reviews I've seen have said the battery life is similar to that of the s5, and probably a bit worse considering the power of the phone and that 2k display. Also there's some bugs in the software and that's the tradeoff with getting the first phone with a new major update. I have read that Samsung is aware of the battery life issue and that a patch should be coming to hopefully improve battery life.
Also during the first week or so there are still some "setup" routines running and you may get a notice or two for features of the phone and such. It may also be updating various apps, monitoring your usage patterns to learn your habits and become better aligned with you. All this will take time and power but will eventually subside.
Setup, Use and location play a huge roll in battery usage. One should not compare their battery time during setup to one not being used in the same manner. I can get 20+ hours on my S5 one day at one location and be fighting getting back to a charger only 8 hr into the next day, simply by my location alone.
Your new battery may need to go through a normal charging schedule before it sets.
i almost passed on this phone because of the reported battery life issues but so far it hasn't been noticeable coming from a S5. I got the S6 Edge. I turned off some of the bloatware as soon as I took the phone out of the box, so that may have helped. with what I would consider light use so far it goes past 24 hours easily. I would guess once I get all my apps on here it will be less, but I will be happy with half that, which is about what my S5 was able to do with heavy use.
Using the edge scrolling info feature doesn't seem to kill the battery any faster either FYI. it's the coolest thing about this phone even if it's just showing the clock.