It's that time of year again when everyone gets hyped over what Google is planning for the future of its projects – it could only be Google I/O. This year is no exception, with talks on everything from smartwatches to virtual reality. Of course, the biggest focus is on the next version of Android – at the moment, it's simply known as Android M.

As usual, the codename is kept secret until a later date, and it's not even known yet whether Android M will become Android 5.2 or Android 6.0. However, what is available now is the developer preview – builds are available for the Nexus 5, 6 and 9, and the Nexus Player. I've already installed the preview on my Nexus 5 and I'll be going over some of the features.

Firstly, the permissions system has been vastly improved. You can now configure permissions per-app to control what each app has access to, and apps can trigger requests for additional permissions while running, without having to have permenant access to these permissions. These features have already been present in some custom ROMs, such as CyanogenMod, and it's likely that Google has taken cues from these.

Next, Android M aims to improve the battery life of devices with new features such as Doze. In Android Lollipop, Google introduced Battery Saver, a feature that limits background processes and dims the screen, which automatically turns on when your phone is low on battery. On Android M, they've taken this further by limiting background processes when you haven't been using your phone for a while, meaning that it won't eat up lots of battery while sitting in your pocket.

Another new feature introduced is Google Now on tap, which allows you to get information about what's on your screen from Google Now. For example, if you have a next saying "can you do the laundry?", you can hold the home button and the feature will let you add a reminder to do the laundry to Google Now. However, this feature isn't finished right now, but in the future it should be able to give you suggestions from lots of different apps.

Additionally, Android M will have built-in fingerprint reading software, removing the need for manufacturers to create their own implementation that differs from other devices. Along with this, Google are creating a rival to Apple Pay, called Android Pay, which will uses NFC for payments and allow fingerprint authentication, eliminating the need to remember a long password. However, biometric authentication has its downsides too.

Other more hidden features include a dark UI which can be enabled in the developer options – enabling the developer options involves tapping the build number under 'About' seven times. After doing this, you'll find an option to change the theme under the menu. Additionally, SystemUI Tuner allows you to configure how parts of your system look, though it's currently limited to changing the layout of the Quick Settings panel. This can also be enabled through the developer options menu.

Additionally, Google have updated the appearance of the app drawer in the Google Now Launcher, which is now searchable and groups apps into the first letter of their names. It also features a new layout – rather than swiping left and right through different pages, you scroll up and down through one long page.

The volume controls have also been updated to allow changing the media, alarm or system volume at any time without opening the Settings app, a feature that was available in Android KitKat but dropped in Lollipop. Other improvements to the UI include smoother animations and additional Quick Settings buttons – however, in general, the UI is still relatively similar to Android Lollipop's UI.

Overall, Android M looks like a very promising release, with few noticeable bugs in the first preview and many improvements. Not all of the new features made it into the first preview, but they're certain to come when Android M is released, if not in a later preview – Android M is the first version of Android to be getting additional developer preview builds at a later data. If you have a Nexus device and love new features, the developer preview is well worth checking out.