It's unclear what exactly they're doing apart from putting an iPad shaped border round an iframe. This doesn't in any way let you "test your website on an iPad". It let's you "test your website in the exact browser you are using right now but with a silly extra border". How is that useful?
The title, blog post, and the about page of the "app" don't mention this. Which is misleading and annoying.
Now, a service that actually let you test your site on an iPad in the manner of crossbrowsertesting.com or even browsershots.org could be very useful. But this ain't it.
With Apple's developer tools installed, open the "iPhone Simulator" and choose "iPad" from the "Device" menu. Open Safari. Voila: your website the way it would (actually) look on an iPad.
The title, blog post, and the about page of the "app" don't mention this. Which is misleading and annoying.
Now, a service that actually let you test your site on an iPad in the manner of crossbrowsertesting.com or even browsershots.org could be very useful. But this ain't it.