WhatsApp is more popular because it is available not only for iOS users but also for all other mobile platforms : Android, BlackBerry, Nokia (S 40 and Symbian), Windows Phone.
You can assume that it is reserved only for phones, not iPad and iPod touch. Thanks to jailbreak commune usage of WhatsApp Messenger on iPad is possible.
We’ll show you how to install and use WhatsApp on iPad:
1. You must have jailbreaked iPad.
2. Download and install the iPhone Configuration Utility from the address below:
Download WhatsApp Messenger. ipa file here http://adf.ly/BRqWA (10MB)
3. Connect your iPad to your computer
4. Launch iPhone Configuration Utility and you will notice the related iPad , left click on it
5. Click the Applications tab at the top of the screen to the right (not left)
7. When you select an app, scroll down and click on the Install Now. The application will appear on the iPad
8. Now run Cydia on the iPad and search for and install a free WhatsPad addition
Run WhatsApp and set it: you have to enter your mobile phone number and you will get an SMS with the three-digit PIN that you enter in WhatsApp on iPad.
You now have a functional WhatsApp on your iPad to send free messages.