I have only had my Note 5 a week, but I can't complain at all. The first night I had the phone it drained from 80% to 30% overnight and I was worried. I am still not sure what caused that, but I cleared cache and rebooted the phone and it's been great since then. I don't need it to last all day, but it does. I have left it unplugged and I go from 100% at 6am to about 25-30% at 9:30pm. That is more than enough for me. Then on top of that fast charging is crazy fast. I have a fast charger at home, work and in my car. I compared fast charging on the Note 5 to regular charging my 6s Plus and it wasn't even remotely close. I started charging my Note 5 at 50% and the 6s at 75%. The Note 5 got back to 100% and the 6s Plus was at 95%, only gaining 20% points in the same time it took the Note to move 50%. That's not to say the 6s Plus has a bad battery. It actually lasts slightly longer than the Note 5. I am just very impressed by fast charging.
Bigger batteries are always good and I hope they increase the size in the Note 6, but I have no complaints about the Note 5 at all.