I got the SE a couple days ago and spent some time getting to know the watch
Honestly it's perfect, if you are willing to not have the Blood Oxygen sensors and ECG sensors.
There are minor differences like an S5 chip instead of the S6 chip found in the series 6
It's very fluent and is speedy fast way faster coming from an series 0 the battery life is awesome
My overall experience I'm highly satisfied with the watch and would not consider the upgrade to the series 6