The main feature the app boasts is the function of showing live streaming of what you are looking at whilst making a phone call. I am going to be brutally honest here...but isn't that simply a replica of Apples 'FaceTime', and any other video calling devices out there. I really don't see how this is any different. I decided on look into the demo (which I have embedded below) and from that inspection it is just what I had imagined. FaceTime / video calling, but with a different interface. I really don't see how they are marketing this as something new and revolutionary. I imagine they are explaining how this is achievable whilst calling on 3G and now 4G networks. However with the iOS6 set to release in the Autumn, using FaceTime on the 3G networks that will then be a normal procedure.
Going further into the demo it explains how you can achieve all these extra functions with Sidecar in 'real time' as they keep repeating. Again, I can't see how these things are incredible functions. You can look through other contacts, browse your photos and other functions whilst on a call with someone. I know without the app you can't send photos to someone 'in real time!', however who is that eager to receive a photo 'in real time!!!' - Surely you can wait until after the phone call to quickly receive the photos via email or text message. With ever faster networks this is being less of a time consuming task. With looking at contacts...well you can just read them out the number whilst on the phone, you don't need proof of seeing the number on the screen. Again, that waiting game after hanging up isn't such a big deal to receive a phone number. And more importantly the trusty pen and paper is has been working wonders for the last couple of centuries and more!
The two functions I do like however, are the tag lines for video calling, and the function to find the location of your friend you are speaking on the other end of the phone. I believe the tagging function would be a lot of fun, and the Google maps integration to show their location is very useful.
However, other than that I really don't see this app as something new and revolutionary. Watch the demo video, to see get your own opinion.