While I appreciate the fact that Gizmo uses open standards for internet telephony, and that it is available for my Nokia 770, it still has to be mentioned that its user interface has a lot to learn from the latest Skype beta. You just have to love the simple, purpose-driven UI:
Hopefully an updated Adium plugin would bring similar simplicity for Gizmo.
In the meanwhile, I could wonder why the VoIP vendors want to stick instant messaging into their applications. Most people already have an IM client they use, and while the one in Gizmo at least is standard Jabber client, I would still prefer to use my own servers and Jabber IDs instead.
Updated 2006-07-26: ThoughtFix has a quite favorable Gizmo-on-770 review. Sounds promising.