Editors' note, February 19, 2014: This review has been updated with information from Facebook's announcement that it acquired WhatsApp.
WhatsApp Messenger (iPhone|Android) lets you chat for free with anyone else who owns the app and offers a few extra useful features to make text messaging more fun. With this chat app installed on your smartphone, you'll save a little money on text charges through your carrier and across platforms. The only catch is that you'll have to persuade your most frequent texting buddies to download the app, too, but once they see WhatsApp's advantages, they'll probably give it a try.
WhatsApp Messenger was recently acquired by Facebook, and while that doesn't mean a big change to the app in the near future, it makes me wonder how Facebook plans to use it. Whatsapp is already incredibly popular around the world, so any news about changes to the app will be watched closely. Should we expect WhatsApp to continue in its current form alongside Facebook's own separate messaging app or will Facebook's offering suddenly have the same features, as Whatsapp rides off into the sunset? It's hard to know at this time, but check back here for more information and an updated review when any new Facebook chat app becomes available.
Like iMessage for iOS, WhatsApp Messenger shows your chats in little text bubbles, gives you a time stamp for messages, notifies you when a text has been viewed by your recipient, and lets you include photos, audio notes, and videos within your conversations. But with WhatsApp Messenger you can also change your background and send your GPS location to an interactive map. You can use premade away notes such as "I'm busy" or "Available" or even "My battery is about to die," and you can block specific contacts from within the app. You also can easily send a friend's contact information to another user without leaving the app. So, while the app is not leaps and bounds ahead of other messaging apps, there are some nice extra features here.
Great for conversations among multiple users
One thing WhatsApp does exceptionally well is group messages. You can use the Broadcast Message feature to bring up your entire list of contacts, then click radio buttons to quickly add contacts for a message blast. There's also a New Group feature, which lets you add contacts for a group message much as you would in iMessage or another chat app. But you can also look back over the group messages and list just the locations or just the media added to the group chat by all members. These are not amazing or groundbreaking features, but they are a bit more than what you can get with the standard messaging features on most phones.
So the real advantage of WhatsApp Messenger is the money you save when communicating with Android (if you use iMessage) or while communicating internationally. In other words, with WhatsApp Messenger, and a little cooperation from your most-texted friends and family, you could easily get the lowest-cost texting plan with your carrier and save some money every month on your smartphone bill. It shouldn't be that hard of a sell either, since your friends will save money on their phone bills as well.
A note about pricing
WhatsApp Messenger is free to download for iOS and Android users. In the past, the app cost 99 cents, but the developers moved to a newer pricing model in the middle of 2013. Now, the app is free initially, but after a year of use, you'll need to pay a 99-cent subscription fee for another year. This is the first time I've seen such a pricing scheme, but it's hard to argue with only $1 per year for a solid messaging app that works cross-platform.
Overall, WhatsApp Messenger is not much different from the text-messaging services you get on your smartphone, offering a few neat extras that make it a little more fun and useful. At this point in time, it's hard to say what will happen now that Facebook is taking control. Until we find out, if you do a lot of texting, this app is still a must-have, giving you unlimited free texts with all your friends, whether iOS- or Android-using, without having to worry about extra charges, even internationally.