Android 5.1 isn't one of those massive life-changing releases that'll have you tapping the 'look for updates' button frenetically for days on end; but nor is it one of those minor upgrades with only bug fixes and technical improvements. Here are the cool new features you're going to get with the new Android—once it eventually arrives on your phone.
In Android 5.1, a swift drag down from the top of the screen brings up the quick settings drawer, even if your phone is locked and protected with a PIN. That means you can quickly turn off Wi-Fi or Bluetooth, or launch the flashlight, without unlocking your phone, but it also means your friends can play around with your phone's brightness behind your back. Watch out.
You may not have noticed it, but activating certain toggles (like Wi-Fi hotspot or invert colors) will add the relevant shortcuts to the quick settings drawer the first time they're activated. In Android 5.0, you couldn't then get rid of them; in Android 5.1 you can, with a long press on whichever button you want to hide, giving you more control over the appearance of the panel.
Perhaps the biggest change, Device Protection, is only available to the Nexus 6, Nexus 9 and new Android 5.1 devices. It's automatically activated if you set a secure lock screen method (like a PIN) and adds various security measures to make it harder for someone else to access your device (for example, your device will stay locked even after a factory reset unless your Google password is entered).
Google is promising high-definition audio that's "crystal clear" in the Android 5.1 update, though you are going to need a compatible device on a compatible network for this to work: The Nexus 6, T-Mobile and Verizon are all mentioned in Google's blog post. If you do have the necessary hardware and a strong enough signal then you should be able to hear your calls better than ever.
Are you a passionate Priority Mode user? If you've never used it before, it lets you automatically or manually shut off audible notifications for a particular time period (when you're asleep, for example). In Android 5.1, Google has added the option to activate Priority Mode until your next alarm goes off (when you need to get out of bed and face the world again, for example).
We don't have a dual SIM phone in hand, but Android 5.1 Lollipop ushers in support for running two SIMs in one phone. No doubt as a nod to those in developing nations picking up their first smartphones, or international travelers. The dialer app lets you choose between your SIMs and will color-code its interface to make sure you know which one you're using.
In Android 5.0, tapping Bluetooth or Wi-Fi in the quick settings drawer would turn these features on and off. Thankfully, Android 5.1 ushers in a much more important capability, which is to scan for nearby networks or devices—tap the small downward arrow by each icon to see what's on offer. Thank you Google, for fixing this small annoyance.
Android notifications now drop in from the top of the screen as they happen. In Lollipop 5.0, you had to dismiss them with a swipe, act on them with a tap, or wait for them to disappear. In Lollipop 5.1, you can swipe up to quickly dismiss them—but this time they'll stay in your notifications bar ready to be dealt with further down the line.
Not exactly worth shouting from the rooftops, but a useful little feature nonetheless. In the dark old Android 5.0 days, tapping the volume buttons while audio was playing only changed the audio volume level—now you can tap the bell icon to the right to modify the system volume level too, and access the various priority and interruption modes, without pausing your tunes. You can change the alarm volume from inside the Clock app too.
You eagerly latch on to your local diner's Wi-Fi only to discover that they let their broadband subscription lapse last month (or there's some other problem with the network). If Android 5.1 Lollipop hooks up to a Wi-Fi network with poor connectivity then it will remember and not try to automatically connect to it again. In the meantime, you can try and troubleshoot the problem on the restaurant owner's behalf...