Geez. Debian is easy.
Thing is that Gentoo is alright for nothing mission critical and all that. I don't like the idea of using it for something important though.
Mostly it's the security and stability issues. There are going to be lots of people using the same binaries and same exact versions that I do. Also all the packages have been thru a rigirious testing and evaluation period (in relative to other Linux's).
In Debian you have several stages that a package has to go thru in order to make it into stable. It starts off in a Debian Experimental branch for that specific role or code base.. Then after it's got basic compatability testing and the developer thinks it's ok for general use it is then stuck into Debian Unstable were it will be used by developers and Debian-advanced/experianced users that weed out any obvious bugs and compatability issues with other software packages.
After passing Unstable then the package is sent to testing were it's then evaluated by another group of users and is given time to get more testing and is eventually joined by other packages that have been thru the same proccess.
After that then the whole thing, packages and OS and all, are then upgraded to Stable.
In stable they go into maintanance were they are only updated when new bugs are found or security issues. The whole OS and almost all the packages used in it are thusly tested for compatability, completeness, and correctness thru the natural proccess that Debian proccess that they've developed over the years.
And then as a end user I can be confident that everything will be compatable and reatively bug free. It's fairly unchanging and very reliable and stable and I know that security issues will be taken care of quickly.
So that, as a end user, if I wanted to create a complex website depending on various technologies... Say for example: Apache web server, PostgreSQL database, various ODBC do-dads for people keeping track of inventory on the Desktop, Zope, Python and various Python modules, Apache Python-mod or whatever, etc etc.. then throw into the mix some propriatory software on a different computer I have to deal with, bunches of custom scripts, html, and stuff developed by other people.
With Debian Stable I can be realtively certain that when I do a "apt-get update && apt-get ugprade" I will end up with a server setup that still works just as well as before I did the upgrade.
If I was using Gentoo (or Debian Unstable for that matter) I couldn't be certain that after doing a upgrade that all the 20-40 different packages that I depend on will still work the same exact way as it did before. There is a lot that could happen... For instance If I use Python-based programs for some Intraweb application do-dad I could end up with upgrading some python modules that may have a different or improved syntax, that while maybe technically superior, may cause some scripts to break. Or something may change with a ODBC connector and it becomes subtly uncompatable with the MS Office-based Excell scripts that the accounts have themselves written in some way. Or maybe a new bug is introduced that crashes the web server...
All sorts of crap like that can cause huge headaches and unintentional downtime.
Then there are numerious security issues. For isntance If I need to allow people to log in remotely to my server and they are not all completely trusted (like they may pick stupid passwords or whatnot) then it's a very bad idea to let them have all this developement software and compilers and all that within easy reach. Linux has enough issues with "Local Root Exploits" without giving hackers the tools they need to root me just by default.
And if you get hacked, you probably wont' know it, unless you have some intrusion detection system running or keep paranoid-as-all-get-out eye on your server. This isnt' windows, it's not going to go BOSD because some script kiddy is running some bad application on your system. It's almost trivially easy in Linux to cover your tracks if you've rooted a system.. as root a hacker would have ultimate power over every aspect of your server, including any logging facilities or virus scanners or whatnot. (which is why people made IDS and SELinux among other stuff)
Now for a personal or for simple stuff using Gentoo as a server is just fine. Personally I use Debian Unstable for everything, which is about the same level of changing-ness.
Other then that the reason I use Debian is because the quality of the packages and 'completeness' of the OS. I don't have anything against Gentoo aside from the length of time that it takes to compile stuff. (I do like lots of Gentoo's documentation though, some of it is very handy)
If you want to give Debian a serious try check out:
Debian GNU/Linux Desktop Survival Guide
Debian Newbie Doc (for newbies by ex-newbies)
The following can be installed by going thru apt-get:
http://www.debian.org/doc/manuals/debian-faq/index.en.html
http://www.debian.org/doc/manuals/apt-howto/index.en.html
http://www.debian.org/doc/manuals/reference/reference.en.html
Usually docs get installed in /usr/share/doc/ but you end up with documentation for every single package and it can get annoying searching thru it all. However if your having issues with certain things it's always best to check there... also for some packages you have something like 'python', but you also have 'python-dev' for when you need to compile packages that may need something extra, also you can have 'python-doc' which will have extra information aviable for you to use. Also checking out /usr/share/doc-base is sometimes helpfull.