Despite the fact that the Drive 2.4 is interesting as disk drives go, the most important feature of a disk drive is that it should be unobtrusive. When you pop a disk into the drive, you shouldn't have to think about what you're doing. The Drive 2.4 must perforce stick out more than an internal Apple SuperDrive, if only by virtue of its design. It is only an external drive, and like all external drives, should sit on the right hand side of compact Macs to avoid the monitor radiation. The manual makes a point of this for users who haven't heard the corrupted disk horror stories.
The main problem with the Drive 2.4's quest for unobtrusiveness is that it does too much. The first thing you can do (though the default settings are fine) after installing is check the settings in the Rapport Control Panel, accessible like any other cdev interface. Rapport has three settings, the first of which controls whether or not the Rapport icon displays in the icon march at startup. The second option determines whether or not Rapport will by default allow you to create non-standard disks, such as 2.4 MB MS-DOS disks. This default setting can be overridden in the format dialog box. The third and final setting tells Rapport if it should control the internal disk drive as well, or if the internal drive should merely perform standard Macintosh functions. You need to switch back to standard Mac functions if you wish to reinitialize an MS-DOS or ProDOS disk to the standard Mac format. The defaults are to show the icon at startup, restrict the formatting options to standard interchange formats, and allow Rapport to control the internal drive.
Once you get down to using the disk, it's completely transparent, so long as you use Macintosh formatted disks. If you insert a MS-DOS or ProDOS (I assume, since I don't have any 3.5" ProDOS disks around), you get a dialog box telling you about the disk's size and format. A dialog box then tells you to eject the disk and run Apple File Exchange to view the disk, or you can reinitialize it directly in a format that makes sense for the disk. If the disk really is unformatted, the dialog box says that the disk is unreadable and provides formatting choices along with the option to eject it.
In the time I worked with the Drive 2.4, I found it eminently usable, other than that stupid little flashing light. I used the Drive 2.4 for my standard Macintosh tasks, like copying master disks and making floppy backups. The only thing that you cannot do with the Drive 2.4 that you can do with the Apple external drive is boot from it. This inability makes sense, in light of the Rapport INIT needing to load, and is not a major deficiency since the Drive 2.4 will almost always be the second drive.
I'll admit that one of my main hopes for the Drive 2.4 is as a backup device. Since Retrospect and other backup programs can compress files up to 50% of their original sizes, I was hoping to put 4.8 MB on a single high density disk. When I tried this, Retrospect never managed to put more than about 3.2 MB on a single disk and MacTools Backup did even worse. This of course is not the fault of the Drive 2.4 in any way, and it's likely that the files I was backing up were not the sort that can be easily compressed. Without having used it, I assume that FastBack II can achieve the same sort of results, if not better, when used with the Drive 2.4. If nothing else, FastBack II is free with the Drive 2.4, an especially helpful bundle from Kennect if you buy the Drive 2.4 primarily for backups. Depending on your backup program, you might even be able to get away with using the 2.4 MB disks for unattended backups at night by leaving a single disk in the Drive 2.4, since 2.4 MB with compression can hold a lot of data from an incremental backup. It would all depend on whether or not your backup program (a) does unattended backups, and (b) if it's picky about getting confirmation. There would be times when the disk would fill up and you would personally have to insert a new one, but that would happen infrequently enough that it shouldn't be a problem for most people.