I've been using the Steam Deck for about a year and it is pretty good although it can be a bit janky. I was having issues with Decky, it always had a notification that it needed to update then the update would fail. Eventually if I just hovered over the Decky icon I would get text garbage on my screen and I would have to restart.
I restored my Deck back to factory settings and backed up some things to my network drive. I took a different approach to installing applications this time, opting to install more things through Flatpak rather than running scripts. DevilutionX and Retrodeck downloaded easily although I couldn't get PCSX2 emulator to recognize my memory card backups, bummer. I tried installing Phantasy Star Online through Lutris but I can never configure it properly, I uninstalled and followed a guide to use the installer downloaded from the Ephinea website.
Now I have the Deck setup exactly how I want and moving forward I'm only going to play games through Steam. Decky does provide some great features, my main use was accessing the Blizzard launcher so I could play Diablo II Remaster and Diablo IV. Oh well, I could probably find a way to get it working in Steam with Proton but I don't think it is worth the time, it usually breaks every time the launcher gets updated.
Since this is the the steam deck post I should probably mention that I am using the base LCD model with 200-some gigs of hard drive space, and expandable storage through micro sd. I gotta say, it is PLENTY of space for the types of games I play. I run it docked at my computer station with a keyboard/mouse switcher, I have a Magic Stick NX that allows me to wirelessly connect a controller at any time. Truly a luxurious system.