ZDNET's key takeaways The new Xiaomi 15 Ultra sees improvements in almost all the right places, with a 200MP periscope lens and a more durable design. The camera configuration is still one of the most competitive ones on the market. If you're in the US, you'll have to pay to play, with conversions nearing $1,555. View now at Mi The moment I unboxed the Xiaomi 15 Ultra, I knew I was in trouble. While the flagship had launched in China just days ago, its global debut today at Mobile World Congress (MWC) should raise some flags among its Android competitors…