Owners of the OnePlus One have been happy to get their hands on Android 5.0 Lollipop due to OnePlus working on the OS in secret.
They did this as there has been lots of controversy in India surrounding the Cyanogen licensing. OnePlus took over and offered Android 5.0 Lollipop to owners of the OnePlus One and this is taking over from the current OS, which is Cyanogen.
Bear in mind that the Android 5.0 Lollipop ROM for the OnePlus One is an alpha build and it was made available on the website along with information on how to install it. It is said to be close to the stock version, with slight changes, with one of these being the option to choose to have onscreen buttons.
Bear in mind that the Android 5.0 Lollipop ROM for the OnePlus One is still in the early stages and so you can expect some issues and bugs.