What distinguishes Gizmo Project from the other services out there, and why is Gizmo Project a better choice?
Skype: Like Gizmo Project, Skype has excellent sound quality, and is able to connect calls even in difficult home networks. Unfortunately, its technology is completely proprietary and you cannot contact their members without installing skype on your own computer.
That doesn't sound like a compelling differentiator to me. I've been using Skype for almost a year now and I have yet to find any other VoIP service that comes close to it in terms of overall tech reliability and scale of its user network.
But you have to start somewhere and competition is good. From a user point of view, Gizmo has many similarities to Skype: a peer-to-peer system, free calls to other Gizmo users, ability to buy credit to call normal phones, get a phone number so you can receive calls, get voicemail, etc. See the full story at Gizmo.
So I'll take Gizmo for a spin and see how it is. I will keep Skype as a) I'm happy with it overall, and b) I have a lot invested in it now (two SkypeIn numbers, for instance). Any alternative would have to be so compelling from many different points of view - wholly-reliable service and price being just two - that switching would be a no brainer.