S5 battery seriously not that good as reviewed by gsmarena.
I had g2 d802 and usually gets 7.5- 8 hours SOT while on wifi all day, while my s5 only managed 6h23m also on wifi. Out of the box it was worse tho, only 4-5 hrs SOT. I got the exynos one here in Indonesia, but from what i read on s5 forum, people having the s801 also complaining about battery life. Only a small number of them passes the 7 hr mark.
Maybe it depends on how we use the devices. GSMArena includes video playback test, which in my case does not concern me. I never watch movies on my phone. From what i heard, AMOLED screens excel in video, while G2's screen memory excels in web browsing, instant messaging, etc, which mostly i use my phone for.
I dont really feel s5 is THAT snappier. I never play games on my phones, mind you. For my use s800 is more than enough
I dont really notice the camera department, as i use two phones and my other one is L1020. Never bothered to really test the cameras on G2 or s5.
1 week after purchase, my s5 bottom flap broken from no fault of mine. I opened the flap normally to charge and i got broken into half. Never happened before on my previous waterproof phones XZ and Z1. Imagine if it did not broke in an instant, maybe half cracked, and i plunged into water in that condition.... Luckily samsung covered that on their warranty, and ordered a replacement flap.
All in all, i'm 70% sure im trading my S5 with my friends' G2+cash in a couple of days,