Buggy, crashes non-stop, not very well optimized. One of my favourite games to release this side of 2020.

I still haven't played a vanilla server, but honestly that's not what Reforger is about. It's a testbed for a new engine, a teaser for what is to come with Arma 4 (in like 15 years judging by how things are going) and most importantly a sandbox for modders.
There's basically two mains types of play:
Modern PTSD - servers like WCS, DarkGru, etc. which offer modern weaponry and equipment on mainly eastern europe stylized maps. Try to guess which geopolitical event from the previous few years inspired that idea...
Vintage PTSD - servers like Vietnam '67. On the surface a similar experience to servers like WCS, but after just 30 minutes you'll realise it's a completely different vibe. Once you charge an american position from the bushes in a 15 men strong Vietcong squad, shouting in proximity chat at the GIs in a mildly racist asian accent, you'll never want to play anything else ever again. The feeling is undescribable and you just have to experience it for yourself.

graphics: looks amazing.
audio: sounds amazing.
controls: tons of weird keybinds, but if you ever played previous Arma titles this will seem down right user friendly in comparison.
community: thank you, very cool.
support: on-going and quite active, always something getting tweaked and/or added.
learning curve: it took me a good few hours before I really understood what I was doing... when it comes to making my loadout in the main operating base. Then you gotta learn everything else. But most people in-game are really friendly and happy to help explain things to you.
crossplay: XBOX has mods, PS5 doesn't for now, so playing on modded servers you'll just be encountering xbox players (more of them than you might think). If you're in a shootout with an enemy on Xbox, just wait for their game to freeze for half a minute (happens pretty often) and then shoot them. Makes things much easier.
price: worth it.
mods: can steal a tuxedo and fedora off a GI and be the freshest looking VC soldier in the server.