It is not ready according to Greg Buckles – http://ediscoveryjournal.com/2013/08/exchange%E2%80%99s-litigation-hold/
The following critical information is not held:
- Folder Location
- Read/Unread Status
- Flags
- Categories
- Reply/Forward Info
Also check out this comment on readiness of Exchange 2013 – http://sourceoneinsider.emc.com/2013/02/15/understanding-whats-new-in-exchange-2013-for-archiving-and-ediscovery/
Exchange 2013 is unlikely to be sufficient for organizations facing a higher frequency of litigation and who have invested in in-house legal staff to perform early case assessment and sophisticated review of content before exporting such content to external legal counsel. –