Sony Computer Entertainment Japan and Asia shared quite a lot of information on the features coming with firmware 2.0 "Masamune," but quite a few more caveats have been mentioned on the PlayCommunity site.

The Share Play feature, which is built into the party chat app, will also follow the rules below:

• You can be in a Party with 8 people, but Share Play can be done only with one of them at the same time. The rest of the Party won't be able to see the screen, but will still be able to chat with host and guest.
• When the host is visualizing any other screen than the game being shared, the guest is shown a "stand by" screen.
• The Share Play time is limited to one hour, and the remaining time is visualized in the Party screen, but you can start a new session immediately after the one before expires.
• Certain games may have scenes and content that cannot be displayed during Share Play.
• While you use Share Play, livestreaming and remote play are not available.
• The guest cannot save video clips and screenshots during share play.

There's some more info also about the USB Music Player app:

• It's not possible to copy music files from USB to the internal hard disk of the PS4.
• The tile of the USB music player will be shown exclusively if the connected USB storage has a "Music" folder. Also, it cannot be used at the same time as Music Unlimited.
• Tracks played by the music player won't be heard while livestreaming and in videos recorded by the PS4.

There's no precise information, for now, about when the new firmware will be released by Sony. Hopefully it won't take too much longer.