I'm having the exact opposite issue -- going from the Pixel 3 to 4, Face Unlock is absolute trash. With FP I already had my finger on the reader as I was pulling my phone out of my pocket / picking it up, and it'd be unlocked and ready by the time I had it held up. Face Unlock fails every other try, adding a few seconds to the unlock, it doesn't work with masks. It's super frustrating and no amount of re-learning is fixing it. Pattern/PIN unlock isn't an option (keep in mind this is also your encryption key for full device encryption), so having to type in a passphrase even occasionally is a PITA.
Otherwise I agree, my battery life feels fine, and the upgrade to the 5 doesn't seem all that worth it.
Oh, in my case Face Unlock is reliable, sometimes to reliable, when I try to put my phone away it suddenly unlocks because my face was near :)
Oh and a trivia about Pixel 4 Soli (which is a gimmick, nothing more), I was wondering why my music suddently restarted so frequently when I was in car.
And I found out why after few days - since a week we have a lot of rain, so when I drive I have windscreenwwipers and this was somehow being picked up by soli (when my phone was mounted near windshield, but not that near) :)
Yeah I had to disable the proximity sensor for the music controls, it 1) triggered constantly when I didn't want it to, and 2) took 4-5 tries when I actually tried to use it (ie swipe to the next song with dirty hands in the kitchen). It's a neat idea, just unpolished.
Otherwise I agree, my battery life feels fine, and the upgrade to the 5 doesn't seem all that worth it.