Advantages: Better Organization, may use less disk space

Disadvantage: More drives to monitor.

I've always been big on partitioning the hard drive. I leave the C:
drive for Windows, Install programs on D:, Use E: to store data, store
media (graphics, videos) on F:…etc

Large hard drives partitioned only once tend to use more disk space to
nest files further into subdirectories.

Things like fat tables will use up the same disk space whether it be
one large FAT on one drive or two smaller FATs on two drives.

It all comes down to this… Any advantages or disadvantages will be
small. It's really a matter of personal preference.

The only major disadvantage I can think of would be a single large
drive is much more likely to get fragmented files… that will slow
down the system. However, if once every few months you run your disk fragmentation tool found under systems tools then this will reorganize the files to run efficiently.