Samsung begun seeding the Android 5.0 Lollipop update for the Galaxy S5 in December. Naturally the update was compatible with the Snapdragon 801-powered model and the first country to taste it was South Korea.
As of today Samsung has started to update the Exynos-powered G900H Galaxy S5 model too. The first market to get Lollipop is Kazakhstan, but we expect more countries to get the new firmware very soon.
In case the Kazakhstani ROM works for your device, you can grab it from the link below.
Android 5.0 brings a host of improvements to Samsung Galaxy S5. The OS is TouchWiz-ed with just a pinch of Material design, so the user experience will not be dramatically different from the one in version 4.4. However, thanks to the brand new ART runtime, you should feel a noticeable improvement in the responsiveness of the device.