These days, a lot of companies are considering a mail migration from the on-premises Exchange environment to the Office 365 cloud. At the same time, they wonder how their Enterprise Vault archives will be handled then. As you'll already know, Office 365 Plans E3 and E4 have "advanced archive capabilities" (I my opinion these built-in Office 365 archiving capabilities are not so advanced).
When there was no cloud yet and all mailboxes were located on-premises, Enterprise Vault was a big help in decreasing the Exchange mailbox database sizes. Now that we have cloud mailboxes of 25GB, this isn't a problem for the IT department anymore.
Although, If you want more control over your archiving settings, more transparancy to the mobile users, and want less costs (if you prefer plan E3 rather than E2 because you only need the extra archiving capabilities of Office 365) than EV.cloud can help you.
EV.cloud looks like a journaling mailbox in the cloud.