Android/iOS: Today, Google's rolling out Allo, the messaging app it previewed at I/O earlier this summer. This is also the first real glimpse we get into the new Google Assistant.
Allo uses your phone number to connect with other users, instead of your Google account, so you don't need to register to send messages. So, it's a bit like WhatsApp in that regard. Once in the app, you can send messages, photos, video, your location, stickers, or emoji. For a brand new messaging app, it's pretty robust.
Where Allo really wants to stand out, though, is with Google Assistant. While you're chatting, the Assistant can chime in with helpful suggestion or tasks. So, for example, if you're talking with a friend about dinner plans, the Assistant can offer to find a restaurant or add an event to your calendar.
Allo is currently rolling out for Android and iOS users. It's not available in Australia just yet but you can register your interest for the app here. Unfortunately, there's no desktop counterpart yet, which puts Allo at a distinct disadvantage to other messaging apps. Still, it's interesting enough to check out.
Google Allo [iTunes App Store]