Yeah, there's really no comparison. They are two very different devices aimed at two very different markets and sold at two very different price points. As has been pointed out, the TF700 is twice the price of the Nexus 7, and if you get the keyboard dock then it's another $125-$150 on top of that. But overall it is a far more capable device.
On the other hand, if you're looking for an inexpensive entry point into Android tablets, it's hard to go wrong with a Nexus 7. There's also something to be said about the smaller form-factor when it comes to doing lots of reading. IMO either one is a winner, but it's a matter of what you want from it. I use my TF700 with a dock and take it with me when I travel as a laptop replacement. If I need something that's only available on Windows, I can always remote into my PC at home (Splashtop THD works well for this) and do it remotely.