It's very user-friendly, easy on the eyes and new software is very simple to install. This old laptop also runs much faster, quieter and cooler now, though how much of that is simply due to the switch from HDD to SSD I'm not sure.
However...
It seems I'm kinda screwed when it comes to GPU driver support. The laptop is from 2011 and has a GeForce 540M, but LM 22 isn't compatible with the official legacy Nvidia drivers for it, which means I'm left with the replacement open-source Nouveau drivers, and it turns out those aren't meant for much more than basic desktop usage. Video playback and Youtube work though, which is nice at least.
Downloading Steam and the emulators I use was such a nice and seamless experience it's quite the bummer I can't make much use of them 
Apparently some guy has ported the legacy 390xx drivers for modern Linux kernels but from what I read success with those is hit and miss at best and you'd better be prepared to restore your system if you run into trouble. Installing the last version of Mint that had those drivers is also an option, as is apparently switching to something like Anti-X. I already have Anti-X installed on an even more ancient laptop, but Mint is much more slick to use and pleasant to the eye.
I also have a few issues that might be related to the display drivers. Adjusting screen brightness in Power Management does nothing, and using the built-in function key shortcuts makes the backlight blink off and on until I hard reset the system. There's also a phantom second 4:3 display titled "Unknown Display" listed next to my laptop's actual 16:9 display in Display settings.
In summary: Mint is cool but my laptop is more of a dinosaur than I had realized
That's such a shame that your hardware isn't playing nicely with Linux but it's really cool that you gave it a try and it's just as cool that you actually like it.
It's hard to fault past you for, years and years ago, buying this laptop without considering Linux compatibility - it's not like this would have been on your radar until this point so of course you wouldn't have given it any thought. Them's the breaks, I guess.
I'll be trying version 21.3 of Mint instead of 22 next and see if I can get more use out of my GPU with that, so fingers crossed. I'm not expecting incredible gaming performance or anything but I would prefer my GPU not completely gimped.
It seems this is specifically an Nvidia problem. The open source drivers for AMD cards are apparently great but since Nvidia are a bunch of dicks the community has been left to reverse engineer what they can. At least there is an option to keep old hardware going.