1. Free worldwide PC to PC calls. You can also buy a phone card although the integration could be better. Voice now works, often better than using the phone, however it's not well integrated, retaining a bolted on rather than built in feel. Example - the VM voice mail notification (you have to have "messenger" "show/hide" "seach bar") for it to be visible. The voice archives are difficult to find without this. There is no "events" notification. I can't identify how a YahooIn call (Future) would be handled, or how caller ID would be presented in the future. The downside of these additions is a lack of control over whether anyone can call or start a chat etc.
2. Photo Sharing: On the plus side Yahoo has enhanced how pictures can be shared. It's another integration. The more I think about it the more I'd like to see it in the actual client, Slide shows should be possible

Emoticons: Yahoo adds some new ones. They are nicely done.

Things I haven't checked but am curious about.

• Is dialup performance better than Skype? How's the voice quality stack up. Yahoo has many more dialup users.
  
• What will the impact on Yahoo chatrooms be? Will better voice change dynamics? Note the beta and previous versions weren't voice compatible.

Overall

Skype still has quite a lead. From recent reviews of new clients Jajah, Gizmo, Wavigo, Voipbuster, all these are lacking what makes for an easy-to-use telephone replacement. In Yahoo's case they have the resources and capabilities to blow Skype out of the water. Still it's only going to happen if they get the basics right and open up to the developer community. That's key if Yahoo is to get linked to the next generation of hardware devices now being released. Otherwise Yahoo could find themselves locked out of the future because they are not compatible with these upcoming products.