One of the best reasons to own a Nexus device is the fact that Google updates them first. You can rest assured that you will always been running the latest and greatest version of Android. The Nexus 9 has suffered from a handful of bugs including random reboots and poor battery life among other bugs. The update to 5.1.1 should fix these bugs and make for an overall better experience on this otherwise fantastic tablet. The Nexus 4 and Nexus 7 have both had the 5.1.1 update for a while now, and the Nexus 9 will soon join the ranks! According to Google the update will roll out to devices starting today.
Via Google