The S3 feels like the "core 2 duo" of smartphones. Clearly not as fast as new phones, but still good enough.
I have an S5. I can understand the move back to USB2 in S6 and above, and I don't know if USB3 is the cause, but my S5 battery goes from empty to full in a good short space of time, so I'm not missing out that much on the super charging goodness. Battery life is still good too. I'm also lucky to be in a country where Samsung have 2 free screen repairs over 2 years.
Hopefully I'll be able to wait for the S8 or 9. I'm impressed with the S7 on paper, and I'm glad they brought back the things that made me dislike the S6. Now for hoping for better Android upgrades from Samsung :)
Of course it would be nice if Samsung at least cared to provide security updates.