So, I have had my S25u for about a week now.
To be honest, other than it being nicer in the hand to hold with softer corners, a slightly flatter screen, I have barely noticed the difference. Yeah, I probably got to bed with an extra 10% battery, but if it's charging when you sleep, it's hardly a big deal.
It's a bit faster, I will admit.
I don't love the change of having the pull down blind do different things depending on where you pull it down. I preferred the old way.