Keep in mind there are limitations to when one can be purchased. I believe you still have to be under your factory 5/60 in order to do it and the cost might even creep up the closer you get to the end.
And, of course, there's the normal warranty "no modifications" thing so the "inspection" is really more when you have a problem. Basically, they'll be happy to take your money for the warranty and then deny you coverage later. It definitely adds a layer of complexity/risk when buying used. You are at the mercy of what the previous owner did. Whether visible or not.
As for the FCA warranties in general I've been VERY pleased and have benefited greatly on mine over nearly 10 years (engine, transmission, manifold bolts, 8.4 radio and a couple other smaller things).