If you have read this blog, you know that I have been playing with Debian packaging. I have created packages on both Debian and Gentoo systems and so, here and now, I offer my final manifesto on how they compare.
So, what is the difference? Debian packaging basically archives an installed version of the tree (etc/, usr/, usr/bin, etc.) with a couple of text files that describe the package. What it is, what it depends on, etc. Gentoo doesn't really package anything. Ever. Gentoo's Portage system is a network of Python and bash scripting that tells the system where to get the parts for the package, how to configure it, how to build it, and how to install it.
There is a deep philosophical divide here. For the package creator, the tasks are almost completely different. In both cases you have to build the package, but in the case of Debian that is almost all you are doing. You are going to build the package, roll the install into one tarball and pass it around. In Gentoo, you are scripting the build for every single user thereafter. You don't give them a finished product, you give them a machine-readable build manual. From the package creator's point of view, it can be a pain in the neck either way. From the user's point of view it's a case of convenience versus flexibility. Debian packages are nice and easy to install. No fuss, no waiting. It's just done. Gentoo's portage system offers endless configurability and flexibility to build your system the way you want it. Ultimately, it comes down to user preference. Do you want the flexibility or do you want it now? There is no right answer here.
There are other concerns for the package creator. With Gentoo, you are more or less recording the build process. Sure, you sometimes have to do some tinkering to get it to play nice in the sandbox, buut those times are relatively rare and for good old fashioned autotools software, it is a piece of cake. Maybe it's just me, but Debian seems far more fussy. There has been some software that I just said "oh, heck. I'll just make install." rather than fiddle any more with the package.
All in all, I like Gentoo's system better. It is simple, clean, elegant, and flexible. That's not to say it is without caveat, but my experience with it has been smoother than Debian. But, hey, who knows? I may write here in not to long about the glories of deb packages--but I doubt it.