Well, it sure does take more than Ubuntu to install. The handbook guides you to a very slim text only install. The only kinda of hard part is to configure your kernel by hand. It's nothing difficult, but it takes a few tries to get it right. Having done quite a few of them, now it seems quite trivial.
From then on, you choose what you want. KDE, Gnome, etc. You can have for example a very limited KDE install without unnecessary bloat (e.g. kde games), compiled for your cpu and with the dependencies you only need. For example, the sound backend of KDE (Phonon) can work with xine, vlc, pulseaudio or gstreamer. I can choose to have only one of them, or two, or whatever. It's up to you. I choose gstreamer since clementine (a music app) also uses it. So I don't have an un-used sound backend installed on my system. Call me weird, but that's how I want it :-)
Another example is when I wanted to install a vdpau capable mplayer on a friend's ubuntu system: I had to search for a good 1 hour for a build somewhere by someone that would install on the specific version of Ubuntu (i.e. it would meet it's dependencies). On Gentoo it's on a terminal: $ USE="vdpau" emerge mplayer. :-)
What takes a lot of time, is of course compiling packages. To give you an insight, going from a text-just-installed-system to KDE, it took I think about half a day on my Core2Duo 8400. I only installed those KDE components that I needed.
Then of course comes the nice thing of these distros. Almost as soon as something is available (E.g. KDE 4.6.3) I can install it right away. I don't need to wait for my distribution to release a new version containing it.
Basically, if you don't care/want to know what's going on with your system (or don't have the time to), stick with Ubuntu. If you like tinkering, try Gentoo :-)
