The Americans hate Huawei and its EMUI to begin with. They cannot help it. There are ALWAYS bugs at the time of releasing IT related gadgets, it takes few software updates to fix that. Now they are cursing Honor 5X software right after its release.
Some noob reviewers, just to get some more views on Youtube even use pre-production or non retail units for reviews and then point out its flaws and then other junior noob reviewers present others reviews in their own way to get some views.
Huawei EMUI needs some improvements, but it is extremely optimized for smooth performance, there is no animations stuttering, no lagging or hanging issues. Whether its Honor 4C, P8 Lite, ShotX or even Mate S, they all run lightning fast in day to day tasks with barely noticeable lags or stutters. It takes sometime to get used to EMUI anyway!.
Even today, Honor 3C (2GB RAM), running in good software and hardware condition is still faster than many latest entry level phones, especially 1GB RAM phones that are always running out of RAM and closing apps in background.