It's a model that has existed on the app's other platforms for some time, though, so users of say, the Android version, will see it as familiar. The app is free, and so is the first year, but after that, you will pay $1 annually. The change to the iOS app brings that platform's version in line with the rest of the company's offerings.
Apple recently listed WhatsApp Messenger as the 6th most popular paid iOS app of all time. While the company might be seen to be losing money with its new scheme, in the long run it will obviously make more, with a continuing revenue stream.
In addition to changing the company's iOS monetization scheme, version 2.10.1 adds a new feature that allows storage of your chat histories on Apple's iCloud. You can either back up your conversation history on demand, or set the app to automatically back up on a schedule.
Notably, if iCloud is cellular-enabled, WhatsApp will use your 3G or 4G data to back up your conversations, which may use more data than you like.
If you set up WhatsApp on a new device or with a fresh install, you'll be prompted to restore your messages and photos. Note that videos aren't included in the iCloud backups.
Version 2.10.1 of WhatsApp also adds a "multi-send UI," via which users can send multiple photos with one click. The latest version also adds URL schema support to enable third-party apps to integrate with WhatsApp.
In June, WhatsApp announced that it had set a new record for messages sent in a 24 hour period: 27 billion (with a "B"). In addition, it said that it had crossed the 250 million active user mark.
Users of WhatsApp and other chat clients are often said to be "texting" without a texting plan. They're not. Text messages ride the carrier wave free, and thus don't use any of your data. WhatsApp and other such chat clients use your cellular data (or, of course, wi-fi) to send their messages.
While to an end user, the difference may seem small, in practice, it's not. With SMS messages, all you need (basically) is a connection to a cell tower. The signal can be extremely poor and the message will still get through.
With chat clients that use data connectivity, that's not the case. While -- due to the aforementioned small bandwidth load of SMS messages -- it's often recommended that the public use text messages to communicate in the case of an emergency, chat clients such as WhatsApp may find themselves hung out to dry when a natural disaster hits.