DiskFailure has a single purpose, to warn you about a potential or imminent hard disk failure before the disk is rendered nonfunctional/data is lost.
It will warn you trough alert dialogs, growl notifications and the menubar icon, it also features* a detailed list of your drives and the monitored parameters for each and a kernel log history of any relevant drive events.
If available all the data is stored in the cloud, the information for any disks or logs is available on all your machines and accessible from either one so you can monitor disks remotely, never lose any history and it is all within reach.