I've used it for a long time before switching to Arch and then Ubuntu. When using Gentoo I used to know more about the different subsystems running - it was a function of seeing what needs to recompile when you update and also having to sort out issues when certain hardware stopped working.

I stopped using Gentoo and Arch because it was just easier to be on the same OS as other devs and it didn't feel like I lost much switching to Ubuntu. Every now and again I'm tempted to go back to Arch, but honestly, there are other things I'd like to play with rather than my OS