How long ago was that? I have installed Arch with archinstall on ~10 different PCs over the last 4 years without any issues. Maybe I just got lucky, though.
Archinstall works until it doesn't. Recently I tried Luks and BTRFS more than 6 times leading to a script error each and every time. Could I have done something simpler and archinstall work? Possibly. But it offers those things out of the box and for it to fail each and every time ultimately led me back to the wiki to do it manually.
I tried Luks and BTRFS more than 6 times leading to a script error each and every time.
This was actually my experience also, so I went back to a manual install to just get it done. I think the archinstall script won't get any configuration of device-mapper/LVM right (including disk encryption with cryptsetup). The disk encrypt setup had even more hoops to go through than just LVM.
Some weeks ago I tried to install Arch on an old laptop, and since it have been many years since I've installed Arch for the last time, and I've heard good things about archinstall, I decided to try it. Nothing fancy: single drive, LXQt, no encryption, auto partitioning...
I tried maybe 4 or 5 times, configuring different settings in the script, and every single time it gave me a broken installation: no GRUB, or no display manager, or incorrect video driver (Intel, no Nvidia here). I supposedly configured all the options correctly, but I never got a working system. In the end I snapped and searched for some video tutorial and installed Arch the old way. I have no desire to use that script again, at least for a long time.