My watch is overheating regularly and full battery life is roughly 6 hours with 4g Bluetooth and WiFi on.
I don't have the 4G version but on my Bluetooth version I had to tun off both Wifi and Location as my battery dropped from 100% to 71% in just over an hour with little use.
Things are much better for me now. I took my phone off charge this morning at around 11am and I now have 88% battery left with no overheating issues. WiFi was always a battery drain for me, and I always had to turn it off (Galaxy Watch, Watch 3 and Watch4 Classic).
My watch is now at 86% (it was 88% when I last posted). Thats a loss of 2% over the past hour and I haven't really used it, but did receive and look at 3-5 notifications during that time. I have WiFI, NFC and Location set to Off.
I took my watch off charge 9h 14m ago and it's battery is currently at 89%. Now, I must admit I haven't used it since then, its been sitting on my wrist mainly as I slept...
I'm going to leave it until it dies in order to get an idea of how long it lasts. Battery does seem to drop rapidly when using the watch though!
I've had to send my 46mm classic back. No matter what I did, I just couldn't get 24 hours out of a charge with little use @ factory stock settings. Hopefully the replacement will get me at least 48 hours like previous galaxy watches.
Stock settings for me included both WiFI and Location being enabled by default. The Watch 4 only has a 20 hour battery life apparently, and you will have to charge the Watch 4 every day with all these turned on.