I love that you can use it with any website or page of your business regardless if there's anything to track at this point in time! It makes tracking user actions much easier by allowing me to do so without having to install another plugin/applet etc..
The only thing i dislike about Wide Funnels right now is their pricing structure which doesn't make sense (why not just have one flat rate?). As far as using wide funnells goes - nothing really comes across my mind apart from how easy everything was implemented into our site.