I'm not going to do much of an update yet as still learning and fiddling and I'll compare to S23U
Screen
Much better screen. Love the flat edges and square design. It feels sturdy and lots of adjustments in settings to personalise it to your own preference. Also I don't seem to get the odd failures of the touch screen I used to get with the S23U although I think those were probably due to accidental touches of the curved screen edges from my palm or fingertips whilst holding phone so much prefer the flat screen
In my experience to find settings use the search box in the settings app to find which setting you require as there are so many different tweaks you can do
Camera AI
I did a quick test of AI editing of a photo I took with my S23U. It was at a concert taken from a distance via zoon so quality isn't great but ok for a test of AI capabilities

Ooriginal image

Image with person cropped, moved and turned round. AI selected the person, filled in the empty space left behind and drew some legs onto the torso
It took me about 20 seconds to open and edit this picture. So my opinion is simply amazing and what a great feature. I will try taking some new pictures when I have time to play but this feature alone is superb. I'm hoping it will be easier to take more natural looking images without all of the enhancements because whilst the auto enhancements can improve a lot of images, sometimes we want real pictures that show how it actually is I.e real. I would suggest an enhace button I.e the phone takes a natural real world photo but you can click the enhance button should you prefer it to be enhanced and more colourful etc (User choice and control)
Apps
I've noticed a few minor app glitches, with the worst offender being pokemon go as it constantly crashes or frequently needs several attempts to start, however others are having similar issues with this app on other phones so this could be due to an App or Android 14 issue and not the device or ONE UI 6.1
Network
I think Internet access is an issue, particularly bandwidth as it seems to slow down or struggle loading sometimes. When I first set up the phone the Internet speed was ultra fast with one sim card in the phone (3 Network nearly 400mbps fastest I've seen over mobile network probably 5g) However after 2nd sim card inserted and WiFi active the speed falls dramatically and sometimes struggles. I'm wondering if jumping between WiFi and mobile data is an issue. I'll do some more specific focussed Network speed tests when I get a chance. I have about 130mbps home broadband, uncapped 5g EE sim card and uncapped 5g 3 sim card. Previously my typical speed via mobile data varies between 60mbps and 80mbps over 4g
The NFC is currently flawless so is Bluetooth
The battery lasts significantly longer than in my S23U
My current impression is The S24 is a substantially more powerful and stable device than my S23U much more than I expected with a few minor glitches which I expect with a new set up and new OS. I'm glad I upgraded
I'll update with more pictures and Network tests soon