"The Nexus 9 is now faster, smooth, more stable, and appears to have better battery life, but not by much. The Nexus 9 is an extremely powerful tablet but the initial Lollipop release wasn’t nearly as smooth as many expected, but now that Google’s refined everything with Android 5.1.1, this device flies. Everything is buttery smooth, fast, fluid, and appears to be running like a well oiled machine.
I’m actually pleasantly surprised by the noticeable increase in performance and general smooth operations. The Nexus 9 still seems to have a little stutter here and there while gaming, which could just be the display, but it is actually noticeably better overall. The update should not only improve the speed and performance, but there should be fewer bugs, and no more app crashes."