I'm only a casual fan of NIN, but I'm a huge fan of Trent Reznor's defiance of the recording industry. I'm contemplating buying the DRM-free downloads merely to support NIN's efforts. It will be great when more bands realize they can divorce big labels and distribute content like NIN and Radiohead have done in the last year.
It is an awesome concept. $5 to download it all is a steal and it's a great way to support the band directly.
Funnily enough, they probably get more money from this method of distribution than they would traditionally for the same amount of music. The recording industry is all about feeding the machine and keeping the artists in check. Having talked about how record deals leave musicians bankrupt time after time with people who've actually been through it, it's neat to see someone with a big enough following to make it stand up and say "nope, not here pal," to the recording industry.