One of the improvements that should be most noticeable with the new update is the better battery life, something that has been a common complaint in Android 5.0. There were reportedly some issues with the way the OS was working with the processor, leading to a heavier battery drain.
We don’t know what the situation is with other devices by Asus, and it’s possible that Android 5.1 is coming to more handsets by the company soon enough. They have been mostly quiet on the issue so far, as is typical for them.
It’s worth noting that Asus are actually one of the companies with the best track record when it comes to keeping their devices up to date with the latest Android releases. Sometimes they take their time, just like other companies, but it’s not rare that their devices are among the first to get the newest versions.
And that’s one of the things that have been motivating people to invest in their phones so actively, as they know that it’s a good long-term purchase. An Asus phone is usually not something that will be abandoned a few months after its release, as is sadly sometimes the case with other manufacturers/devices.