How the Two Flagships Compare After a Full Year of Use

The smartphone market has moved quickly in the past year, and the performance question between the OnePlus 15 and the Samsung S24 Ultra has become more relevant as both devices mature. Each phone launched with top-tier hardware, but how they behave after a year of real-world use shows clear differences that matter to long-term users.

The OnePlus 15 arrived with Qualcomm’s newer chipset generation, giving it a natural peak-performance advantage on paper. Its raw CPU and GPU output remains impressive today, especially in demanding tasks like gaming, rendering and AI-powered features. Even after a year, users report that the phone maintains strong speed and responsiveness in sustained workloads.

The Samsung S24 Ultra, meanwhile, launched a year earlier but has held up better than expected due to Samsung’s heavy optimisation and long software support cycle. Its chipset continues to deliver smooth everyday performance, helped by consistent system updates that keep ageing slowdowns to a minimum. Most S24 Ultra users still experience fluid app switching and stable UI behaviour even after 12 months.

Thermal performance is an area where the two phones diverge. The OnePlus 15 can hit higher peaks but is more prone to heating when pushed for long gaming sessions or continuous camera use. This can lead to momentary throttling in extreme conditions. In contrast, the S24 Ultra maintains more predictable thermal behaviour over extended periods, even if its peak power is lower than the newer OnePlus.

Battery performance after one year also shows the difference in design approach. The OnePlus 15’s large cell retains strong endurance and still offers a full day for most users, particularly with updated power-management settings. The S24 Ultra has experienced a more noticeable battery dip for some owners over the year, though its efficiency-focused software keeps real-world usage respectable.

Gaming and high-intensity graphics tasks give the OnePlus 15 a clearer lead. The combination of its newer chip generation and faster sustained frame rates provides a smoother experience in modern titles. The S24 Ultra remains capable for gaming but can no longer match the top-end output delivered by the newer hardware in the OnePlus 15.

In day-to-day tasks, however, the gap is far narrower than raw benchmarks suggest. Scrolling, social apps, messaging, video calls and general productivity feel similar on both devices. Samsung’s consistent optimisation and long-term tuning ensure that the S24 Ultra does not feel outdated despite its older chipset.

AI-powered features, which rely heavily on newer hardware acceleration, are another area where the OnePlus 15 pulls ahead. Tasks like live translation, smart photo enhancement and on-device processing run faster and with improved accuracy over time. The S24 Ultra supports similar features but executes them with slightly slower processing due to its older generation NPU.

Long-term software support also plays a major role in perceived performance. Samsung provides an extended update window, meaning that the S24 Ultra will continue to receive refinements that help it age gracefully. While OnePlus also offers long support, Samsung’s track record in keeping older hardware polished remains one of its biggest advantages.

Overall, the performance gap after a year is clearly defined by use case. The OnePlus 15 is stronger for those who push their phone hard with gaming, AI tasks and sustained workloads. The S24 Ultra remains excellent for balanced everyday use, stable thermals and long-term reliability. Both devices hold up well, but the OnePlus 15 has the advantage in raw performance, while the S24 Ultra continues to shine in sustained real-world consistency.

For most users, the choice depends on priorities: maximum power with the OnePlus 15, or long-term stability with the Samsung S24 Ultra.