Installing, maintaining, and updating the PROe server is trivial on both Debian Linux and OS X. (One-click updates directly from the administrative console would be a nice addition, since locating update files on the Code42 site is not as quick as it perhaps should be, but that's a minor nuisance).
Likewise, installing and configuring clients is fast and easy, and once the client software is installed on a workstation, the administrative console allows control of all client settings, saving legwork. Client access can be restricted to ensure that backups are not interrupted, and CrashPlan PROe has a complete set of legal hold tools available in a separate administrative interface should your organization require them.
The client is lightweight and offers good granular control over bandwidth use. The server is extremely flexible, allowing any number of storage points on any number of running servers, even across server platforms, and the CrashPlan architecture further allows any client to be delegated as a storage point for other clients, in the case of, for instance, a satellite office scenario, disaster recovery, or server maintenance.
The only real operating nuisance I've encountered is browser incompatibility with the otherwise lovely administrative console, which does not scale properly for Mobile Safari, and which presents a baffling "server disconnect" message on Safari for OS X. On the desktop, one can simply use Firefox or Chrome, but a proper mobile Safari theme--or even the ability to permanently eliminate the client download prompt when accessing the console from a mobile browser--would be a huge improvement for those of us who do an increasing amount of our admin tasks from our mobile devices.
The ugly is that this wonderfully designed, private cloud backup system, which was once my first choice for small business clients, is now available only in packages of 25 licenses and up. Not only does this make no sense from a supply side—Code42 incurs no storage or infrastructure overhead from private cloud backup, so one would think they would prefer to sell these licenses—but it arbitrarily shuts out small businesses from a product which is otherwise perfect for the small business use case, forcing these businesses, often creative firms which generate multiple gigabytes of new data each hour, to rely on Code42's public cloud product (try uploading 2 terabytes on virtually any broadband connection in the US) or, more realistically, to look elsewhere for onsite backup solutions.
I used to recommend CrashPlan PROe to all my small business clients. I can no longer do so, not because the product is not excellent—it is—but because Code42 literally will not sell it to them if they can't buy 25 or more licenses. The mind boggles at whatever bean-counterish logic led to this decision, which both locks small businesses out of an otherwise ideal product for their needs, and amounts to Code42 throwing away all potential revenue from those in the small business sector who cannot rely on public cloud backup alone.
I'd encourage small businesses and consultants working with small business to contact Code42 anyway, and put some pressure on them to revise this policy. CrashPlan PROe is otherwise as close to a perfect product as I have seen in the last ten years of IT, and it is simply foolish to refuse to sell it because a client has a smaller budget or smaller needs.