Hydrogen OS is an alternative ROM for OnePlus One users that quite unlike its Oxygen counterpart — it’s a redesign of many of stock Android foundations, especially in regards to organization and aesthetics. Hydrogen OS features eye-catchy animations and a design that is reminiscent to both Material Design and Aqua with similar behavior to the former but enough differences to make it unique.
While Hydrogen OS is still in beta with a release scheduled for July, you can try out the ROM on your OnePlus One and enjoy it without registering for the beta. XDA Senior Member natheux has now shared with us a download link to the latest release, and this version brings new animations and general improvements to the aesthetics and performance of the phone, as well as better wake-up gestures. However, keep in mind that early reports in both the XDA thread and the OnePlus forums seem to paint this release as a hit or miss — some claim great battery life and performance, while others claim that there are problems with the touchscreen, gestures, crashes, freezes and even an alleged bricking.
If you do proceed, make sure to read both threads  carefully so that you minimize associated risks. Those of you who want to jump in might find quite a surprise, and the early reviews and screenshots look really good. You can find a video review of the v4 release below, where you can learn about its performance and features.
CREDITS & SOURCE: XDA