A recovery pass can be halted and resumed later if need be, especially if the time estimate for recovery (which is gratifyingly accurate) runs into hours. A full scan of each of my 8GB devices only took about 10 minutes, although the "unformat" option (see below) easily doubled that.
Recovery searches can be performed on either the space marked as free or on the entire drive, regardless of what files already exist. One feature that goes hand in hand with this is the "unformat" function, which analyzes the entire drive for file system structures instead of simply looking block-by-block for valid files. This is useful if you want to recover directories instead of just files (although for the most part I was happy just to get the files back).
It's even possible to recover from a device whose partitions have been damaged or which has bad directory information. You can also add your own custom file types to the program if you're looking for files that aren't in PhotoRec's dictionary of signatures.
PhotoRec restored everything I was looking for, although file names weren't recovered and CR2 files weren't saved unless I enabled an expert option to save "broken" files (possibly because they were seen as damaged TIF files). Also, even though PhotoRec runs on Windows, don't expect a GUI: it has a command-line interface.
You also need to pay close attention to each of the available menu choices, since some of the most crucial options are not obvious. Finally, the online documentation isn't what it could be -- options like the FAT32 unformat command, for instance, aren't clearly explained there.
The lack of a graphical user interface for PhotoRec may be intimidating for some, but the sheer power and flexibility of the program can't be denied. I recommend that advanced users start here; they won't regret the extra effort needed to make the most of the program.
Price: $69.95 (Standard); $99.95 (Pro); $299 (Technician). Free trial available (only previews files)
OS: Windows 98 and later
Recover My Files comes in a few different iterations. The version I reviewed ($69.95) helps you recover a variety of file types from conventional FAT/NTFS partitions; there are also Pro ($99.95) and Technician ($299) versions that both add HFS and RAID support. The Technician version also includes a USB hardware dongle that activates the software. If you only need to restore image files, GetData also offers a $39.95 app called Recover My Photos.