I bought this unit online after the Philips iSight didn't work (the video was way, WAY too slow on my Wireless N network to be of any use, and the audio had a delay of almost 30 seconds, when it worked at all).
This unit, while it does not have video, is far superoir to the iSight. The most beneficial feature to me is that you can adjust the level of background noise the unit transmits to your phone. If you set it high, you'll have an open channel and hear everything. But if you play with it a little, you can get it so that you only hear the sound when your baby is crying - the rest of the time it's silent.
It runs well in the background of the iPhone, and doesn't use much battery power. The setup was extremely easy and very straight forward. Again, the setup for the iSight was a nightmare - I had to change the security settings on my router to get it to work.
Don't bother with the iSight - WeMo is way better, easier, less expensive and overall a better product.