There are RF compliance issues, if you don't exactly follow the TI reference design rules and antenna selection. And the design rules are tough to follow (weird board thickness, etc.) There is useful discussion under the hackaday link alvarolb posted...
You get a bit disillusioned when all those lovely $12 modules become $40 boards, and your homemade "simple" replacement isn't legal :-(
It'd be more productive to write TPLINK router code to turn it into a slave device, and then you wonder what your arduino is there for at all
I agree...that's why I'm hoping someone else does that part...
I actually wouldn't mind a CC3000 daughterboard at $40 if it had more of a normal footprint (not necessarily a real shield, but something more like the hackaday board).
It seems like the WiFi for Arduino right now is either
* Expensive and weird (the official Arduino WiFi board or the Yún)
* Cheaper but limited API (the RN-XV)
* Cheaper but requires "cloud" services (the Electric Imp and the Spark Core)
* Cheaper but in a form factor not great for small embedded systems (connecting an Arduino to a router per your example)
My hope is the CC3000 will let us get past all of that.