I wouldn't go that far.
It appears to be largely useless considering that most every other function it has is better served by other, more specialised applications. (Which, if you're dealing with that file type on a regular basis, you'll have installed anyway. IF YOU DON'T YOU'RE DAFT AND DIE.)
It would have been right at home on the Amiga, MS-DOS or very early versions of Windows, where a single application that does some basic stuff to a lot of files would be handy. (The Amiga had Multiview/QuickView, a WB 3.0 commodity similar to irfanview. MS-DOS had a bunch of very similar utilities done by a very recurring company that liked to do DOS apps using the early Mac font. (They had an 'interactive-product' maker where you could place buttons and make a basic menu, anybody remember that?) Early Windows didn't have anything, which is where Irfanview came from, I guess.)
But it has the unique ability to look through nested directories and interrogate and replace IPTC data, so hooray again.