I'm coming from Gentoo myself, and I've tried to get Guix working on Gentoo a couple of times over the years, and have always been frustrated by how much work and hacking was involved in doing so. I'm no Linux novice, either. I've been a professional Linux/UNIX admin for decades, I know and love Scheme, and am no stranger to putting in a lot of work to get something to run on Linux, but I failed in two major attempts with Guix, despite having lots of thorough assistance from Guix developers on #guix on IRC.
So back to Gentoo's package manager I went.
A typical user would not have put in nearly that much work to trying it out, nor would they have had the skills or knowledge to get nearly as far as I did. Though, to be honest, I did have some requirements (like doing my own compilation of everything on my own old, slow laptop, just as I'd been doing with Gentoo, and not trusting their binary distribution) that a typical user would not.
The other lesson I got from my last attempt was that trying to compile everything in Guix from scratch on an old laptop is just way too slow. Doing this on Gentoo is slow and painful enough, but it's way worse on Guix, and simply unworkable. You really have to have a fast, modern system (or offload your compilation to another machine which will crank away for weeks on end and that you can then download the binaries from) to constantly compile everything you need for Guix.
That said, Guix has really come a long way over the years, and it's impressive to see how far they've come, and I'd absolutely love to see them succeed, but they've got a long, long, long way to go.