Just a few years ago, messaging services that sought to replace SMS were few and far and far between. Among them, WhatsApp(free 99-cent annual subscription) quickly gained a reputation particularly abroad, as the space boosting hundreds of thousands 9f user, it was the service. But a lot has changed since we last took a formal look at WhatsApp. The mobile messaging space is now extremely crowded, and while WhatsApp has added critical new features like web messaging and voice calls .