I upgraded from the OnePlus 8T after almost 4 years of flawless operation. It crossed my mind to get the S25 Ultra, but 1) I can't part with the slider on the side, 2) I can no longer compromise on mediocre charging (the 65 watts of the 8T spoiled me), and 3) while everyone expected that Sammy would also include a silicon-carbon battery, they didn't. So, already coming from OnePlus and having gotten used to its goodies, I didn't hesitate and snagged the 13 in the 16/512 version.
POSITIVES
*Battery: I'm blown away. It gave me 8 hours of Screen-On Time with Bluetooth and data constantly on, the screen at maximum resolution, and a long usage duration with games. With lighter usage, it easily gets 9-10 hours of active screen time. And as if that wasn't enough, it charges like a rocket. Personally, I use the charger from the 8T, which is 65W, and it takes around 30-35 minutes to charge from 15%-100% (the same as the 8T, but with a much smaller battery).
*Display: Amazing resolution and brightness, one of the best on the market. I come from the 120Hz of the OnePlus 8T, and despite that, the difference between the two panels is noticeable to the eye.
*Processor: Qualcomm's flagship, I won't dwell on the meaningless benchmarks as these numbers prove nothing. With the SD 865 of the OnePlus 8T, I never lagged anywhere in 4 years of use. The average user won't notice any difference between the top processors. Where the difference is noticeable is perhaps in efficiency and battery life. One thing is for sure, this processor won't lag anywhere for the next 3 years.
*Camera: Incredible work by Hasselblad on the colors. More natural, less oversaturated than on the OP12 that I've tried. Its zoom is amazing, and overall, the camera is a tremendous upgrade from the 8T. Day, night, indoors, portraits, videos, all significantly better. I don't have an opinion/comparison with the S24/S25 Ultra and iPhone 15/16 Pro (I include both generations since they essentially have the exact same sensors as the previous generation), but let's not overlook the fact that the above devices cost 200-300€ more before we even start comparing.
*Design: I have the Black Eclipse version, and personally, I think it's the best looking. The blue with the faux-leather texture on the back felt "cheaper" to me, but that's a matter of taste. Overall, it's a sturdy device, with incredible waterproofing and a premium feel.
NEGATIVES
*Display: I was eagerly waiting for this generation after seeing the OnePlus 12 and hoped they would eliminate the curved display. For some reason, OnePlus decided to continue this "joke" this year. The 14 will surely have a flat screen since the curved trend has come and gone.
*Packaging: Here, it's not OP's fault but the EU legislation. The charger is no longer included in the package. And the cost of the original with 100W charging? 69€ on the official site! For now, I'm charging with the 65W charger from the OP 8T. I can't imagine how much faster it would charge with the 100W one.
At 1200€, which I got along with a gift of the OnePlus Watch 2R, I think it's the most value-for-money flagship available. I don't know if it has anything to envy from Sammy and Apple; personally, when I considered getting the S25 Ultra, I felt I would be making a compromise for less. I would miss the OnePlus slider, I would miss the incredibly fast charging, and I would miss the incredibly smooth UI of Oxygen OS. 2 out of 2, OP won me over as well, just like the first time I got the 8T, I was choosing between that and the Galaxy S20 Ultra. I definitely got a device back then with an inferior camera compared to the S20, but the features that impressed me determined my current purchase.