Have used it for about a week now and from a speed and reliability standpoint it has definitely outperformed the Wemo app. I also like the added feature of being able to group devices, something the Wemo app doesnt do. The fact that it doesnt work outside my network is no big deal. You will always need the Wemo app for controlling devices outside the network, creating rules and adding new devices, but for around the house, this app is what I use.
I should also mention that there is Mac based app made by the same people that functions in a similar fashion.