Let me start by defining Dolly Drive's five services to distinguish them. Dolly Drive's initial service was Cloud Backup, which remains at the top of its offerings. It can also manage local backups using Time Machine, providing scheduling and file inclusion by folder location in a way that Apple's built-in feature lacks. This feature works fine in testing, and is indistinguishable from a local Time Machine backup, except in the limits of data transfer over your broadband connection.
Its Clone feature resembles that of Carbon Copy Cloner or Super Duper! without the same depth of features, such as scheduling. Clone inexcusably lacks information on its plain progress meter that would let you know the true extent of progress, an estimate of time remaining, or other feedback. Clones can take quite a while. And its process for selecting a source and destination volume leaves something to be desired in terms of feedback about making the right choice and the action to take place. It would be nice to have a summary that said, instead of Continue and Abort buttons, "Drive will be erased and completely replaced with a clone of drive." It can perform incremental updates to cloned drives, however.
But the real gold is in Dolly Sync and Dolly Space. In the simplest explanation, Dolly Sync is Dropbox and Dolly Space replaces iDisk. The distinction between the two is fairly clear. Sync is confined to a folder on your Desktop. Anything dropped into the Sync folder remains on your local drive, is copied to Dolly Drive's central servers, and is then replicated to any other computer on which you have Dolly Drive installed and the Sync option enabled. Sync combines local and central storage with replication. Remove something from the Sync folder and it's removed everywhere. This works exactly like a Dropbox (or SugarSync, Google Drive, SkyDrive, or Box) sync folder.