Debian has a major advantage. Huge amounts of volunteers. Huge amounts of packages. Although RedHat is beating them out (by far) for small, independant software developers making their own packages, Debian developers have pretty well covered the OSS and frequently-used-non-free software spaces.
The thing is, their packages are maintained in such a way that they're *designed* to each be maintained by one person. So the commercial clones of debian won't be able to keep up -- they're designed for easy maintenance of the package, not personal accountability of the maintainer. If that's what your after, redhat's 'pristine-sources' technique is probably better.
I think that debian is probably going to be synonymous with "operating system" one day. It's really infantile right now, but although the implementation is bad (PAINFULLY bad) in some places, it seems to be the only distribution with the right things put into it from the start. You only really need to install it once -- just apt-get update from then on. The more people that use it, the more software will be available and the more feedback will be available on the basic packages to improve them.
Value-added corporate propositions are a Good Thing, but the best good they bring is that they'll eventually be folded into the distribution they were copying from and thus standardized. Since no matter how "compatible" Corel is with debian, unless it is debian, it's not going to be able to install each and every package I might be interested in.
So while I can't recommend it seriously for anyone getting started on linux to use, i'm going to start contributing a bit to the community effort behind it, and hopefully one day I will be able to tell my grandmother, "Oh, you don't need windows. Just use Debian. It's better."
I imagine that by the time that's happened though, RedHat will be selling something Debian-based, or else would have incorporated all of the functionality of Debian. It will be interesting to see what happens, since debian has a bunch of revolutionary ideas which I think embody the spirit of the linux movement; however, RedHat has perfected taking software and actually makin it useful to people. These two things can't remain at odds foerver (well, they can, but that would be bad) and I hope the petty politics between their users don't keep them from unifying to make something great.
hpylg