Xiaomi devices have received 30 percent boost in performance and 10 percent boost in battery life after updating the device from MIUI6 to MIUI 7. However, the stable version of the update is still not available. You can try developer ROM, but only Chinese version of developer ROM is available.
Battery life test has been permed among three device; Xiaomi Mi 4, LG G3 and Samsung Galaxy S6. These all feature 2.5 GHz Snapdragon 801 SoC. Xiaomi has 3080 mAh battery, LG G3 features 3000 mAh and Galaxy S5 got 2800 mAh. All three devices are running on MIUI 7 ROM.
In the test Samsung Galaxy S5 dies first, in 6 hours and 43 minutes. LG G3 dies in 11 hours and 3 minutes, and Xiaomi still has 34 percent left.
Even we compare mAh power, Samsung should have gone longer. LG G3 features a 5.5 inches 2K display, so it seems to perform well compared to FHD display. Mi 4 turned out the winner though.