From the GSMArena story:
WhatsApp has started rolling out the two-step verification feature to users of its Android, iOS, and Windows Phone apps. The security feature was available to beta users for quite some time now, but it has now been made official.
The feature allows you to create a six-digit pass-code that'll be required whenever your phone number is being verified on the app. The two-step verification feature can be activated by heading to Settings > Account > Two-step verification > Enable.
The feature also allows you to add your e-mail address, something which is optional but can be useful in case you ever forget your pass-code.
Keep in mind that WhatsApp won't verify the accuracy of the email address you enter, so you need to enter it carefully to make sure that you're not locked out of your account if you forget your pass-code.
Also worth noting, via MSPU, is a facelift:
WhatsApp has just updated its Windows Phone 8.1 and Windows 10 Mobile app to version 2.17.52. The new update continues WhatsApp’s trend of modernizing its design standards to conform to Microsoft’s new universal Windows app design language without actually updating their app to support Microsoft’s new platform (As only 15% of Windows phones can run UWPs, but ~90% of modern devices can run Windows phone 8.1 apps).
The redesign focuses on the homepage, with the Windows Phone 8.1 style pivots being ditched for Microsoft’s new Pivot style found in apps like the People app and Photos apps.
Furthermore, WhatsApp has also lifted the sharing limit from 10 images to 30 images, so you can now share more images at once instead of having to share in batches (useful for sharing holiday photos on family group chats)
You can download or update WhatsApp here in the Store. Again, that 15% comment looks strange, since at least half the Windows Phones sold CAN be upgraded to W10M and thus to run UWPs, but the reality is that Microsoft never pushed the upgrade, so most casual users just don't know about it!
Comments welcome if you use WhatsApp regularly - is the Windows Phone client right up there with the iOS and Android versions? Me, I think I'll stick to Skype - this has its issues, but is essentially baked into the platform now and works via a data-only login and doesn't get tied to a particular SIM card!