I've been googling on how to get whatsapp working on the N7 3G. I've found link after link where people have been trying and testing it, some with success, others failing. Almost all the guides mention the need for files such as AppGuard and BlueStacks etc.
After reading through pages and pages, it seemed like most people fell into one of these categories:
- they were trying to get it working on a rooted device
- they were using the wifi only N7
- they wanted the same number for whatsapp on their N7 as their phone
For me it was none of the above so in the end I thought I'd just try the obvious. I went to this link via the N7:
http://www.whatsapp.com/android/
Downloaded the latest version of whatsapp and installed it. It works!