For those that have never used voice services that have web management Gvoice will be entirely new. For those that have .. Not so much.
What you should expect from IP voice services is call logs ( useful for contractors and those of us that bill by the hour), voicemail that is web excesssible, downloadable and provides email and SMS alerts. Multiple line and number support typically comes with the territory including things like call hunt.
Google voice has one interesting plus an one minus over other services. The ability to connect point to point via the web. This is not typically availible with other services. Create a call via the web interface ( including mobile) and it will call you ( including mobile) and then your other party. This completely bypasses outbound toll calls especially from your cell phone. This is a massive help as most voip services, like Skype, will not run over mobile data services. This includes 3g connections on my iPhone. That is a massive plus.
The minus is this is not really a phone service. Sorry, you heard that right. This is a call manager. You still really need a voice service; landline, mobile, or VOIP to terminate calls.
Next I’ll be looking at the group management and call screening.