Will it be as big a hit as We Rule was? It's hard to tell; the gameplay is certainly proven already, but one of the draws of We Rule was that it wasn't just a FarmVille clone, and obviously, this seems to be borrowing at least the setting from Zynga's popular title. Of course, another reason that We Rule was so popular was because it had the iPhone all to itself, and now FarmVille is up and running.
We'll see, though. Ngmoco has certainly shown that it's constantly learning about how to find success on the App Store; I'm sure the company has taken lessons from We Rule and GodFinger, not to mention that their development method allows for plenty of quick updates and changes if things don't work out right away. It's been fascinating to watch Ngmoco's experiment, and We Farm (along with We City, another adaptation planned for release soon) is their next step.