Tape is slower, can be bulkier, and not to mention with a Blu-Ray Burner, I have a few TB of data stored before you even finish buying a modern Tape Drive.
That said, I am considering investing in a tape drive in a few more years for bulk backups if I end up going the route of starting my own business. They just seem like a good idea to go along side redundant disk drives, and off site data storage.
If you're going to include the time to buy a tape drive you should include the time to buy a blu-ray burner :-p
But yes it's a good amount slower because it has to be read in order unless you have some sort of ridiculous random access tape drive, which would be mechanically awesome.
edit: I guess if you were going to do that you could just get a blu-ray disk with billions of reading lasers.
They do? I thought hard disks are used these days. Just slap a few RAID SAN devices and be done with it, access over network using your protocol of choice.
They're used for archiving old data. Data that doesn't need to be accessed more than maybe once a year/once every 5 years. Why would you want to buy a networked device and pay for it's upkeep when it will only be used once before it is outdated?
There is nothing inherently better about optics.
There are a lot of things inherently better about optical media, but I was just kidding anyway.