I have a desktop pc more than 5 years old. It's 64 bit, from the first 64 bit proccessors that came to light. It's nice, I don't need something better. This pc is used by me and 3 other users of the family. So, it must always be workable and not a matter of experiments.
I installed gentoo in this system almost immediately after I bought it and guess what, I still have the same istallation with the difference it's more modern than the latest Ubuntu and Fedora. I remember back during installation I had a hard time to setup gentoo. I needed 1 whole day to make my system workable and over 3 days to bring it to the point I really liked. But that was all. I worked for three days five years ago and since then I have the most modern OS, the less bloated and the fastest one.
Now, how I keep it up to date? Each weekend I run an update. Usually, there are a dozen of packages that have updates. The proccess even if needs compilation is automated and in less than 30 minutes, while I surfing, are ready. Ofcourse there are some packages that need a lot of time to be compiled, especially in older pcs like mine. For these, there are always and binaries if you want to use, like Firefox and Openoffice. But still even Firefox needs 40 minutes to be compiled in my system. It's not so hard and it worths the time because the final binary is faster and you can choose if you like your build to support dbus or gnome or iceweasel etc. The same for Openoffice. I build it myself because I don't want it to support java. I admit it needs over 6 hours but the proccess it's again automated and I let it go during the night while I'm sleeping. I remind you though that there are always and binaries if you want to have it in a few minutes. Ok, you can still say that you spend some time each weekend for these things. Well, is not really more than the time someone needs to update his Ubuntu from 8.10 to 9.04 and then the occasianl updates he does.
Also, the people usually have the missconception that the benefit of gentoo is to be fast because you can optimize it during compilation. While this can be true, is not the great advantage of the distro. The real benefit is the so called flags, with which you can choose what options the packages you build you want to support. For example, you choose if you want, beagle or tracker or xmp or doc or even gnome support in your nautilus. And you don't have to do this all the time, you can choose these options in a config file were they are stored permanently. This reduce the bloat to minimum and finally you have the applications you really need in your system.
So the conclusion is:
gentoo is for the mature Linux user ofcourse and while you can not jump to your friend's home and install it in a matter of minutes it has other really important benefits. It's installation is a real trouble but you do it once and for all and after that you really relax and you have one of the best things the Linux OS has to offer. Fast, simple, always modern and greatly customizable.