I bought a base model S25 back in February, but never even used it. At that time, the Spectrum Mobile deal was too good to pass on.
I finally am switching from the old S21 Plus, which has served me well.
Some impressions. Samsung Smart Switch worked well, better than the last time. I was able to exclude over 66,000 log files. Probably a bunch of crash dumps since 2014. I sort of feel Smart Switch is a little too easy; you just confirm the old unlock PIN and it's off to the races. I feel as if it should be slightly harder to clone a device (should they force a Samsung or Google login? Not sure.)
As it turns out, Smart Switch transferred everything from a device running One UI 8.0 to a new device that was running One UI 7.0. iPhoneOS does not allow such a
downgrade restoration, presumably because app data could easily implode.
I don't know if I'm imagining things, but the old screen's colors look better? Did I forget to enable Samsung's inaccurate vibrancy? No, that's not it.
The old speaker definitely sounds better.
I seem to have lost fast charging, but maybe that's because I haven't been using a PPS charger.
Software updates are stupid. Since my S25 has never been used, it has to install each successive update one by one. Why couldn't it jump right to September's One UI 8.0 update, then apply the next two? The One UI update was nearly 4GB! IIRC Samsung never bothered to implement Android's dual OS slot architecture (
until now). Storage I/O seems blazingly fast so the updates are going about as well as they can (they weren't that bad on the S21+). Over an hour later, all 8 updates are mercifully done.
The One UI 8.0 update did something mildly interesting. This phone came from Spectrum Mobile, and had the carrier branding. But I'm actually using T-Mobile service, and the new OS offered to de-brand Spectrum and replace it with T-Mobile. Naturally, I said OK.
Lastly, the S21+ is in pristine condition and feels great out of the case. I think I'm too chicken to use a new phone naked. I thought I would mind a lot that the S25 is smaller, but it doesn't seem to bother me. I prefer long upgrade cycles, so perhaps next time it'll be an S31+ or foldable.
What I may ultimately regret most is the base model has only 128GB of storage.

Actually, I have a lot more storage free now than before; that was not expected. 66k log files is a lot of waste, but those should mainly be single cluster (64 KB on ext4?).