I completely skipped the PS4 gen, but thanks to the PS5 being able to play PS4 discs, I've been playing through some of the big titles that I missed.
Ratchet & Clank - a fun reboot/reimagining. I enjoyed my playthru of it, and if I didn't have other games I wanted to try, I'd probably check out the the "Challenging mode". (Basically New Game+ feature where you play thru it again with more/tougher enemies, but you keep your gear/upgrades)
Infamous: Second Son - Really fun game. Played thru both the Good and Evil story lines. (It's a pretty straight forward platinum trophy for anyone interested in that sorta thing)
Crash N'Sane Trilogy - Another remaster with some added features that the original games were lacking. It's one that looks great now, but still simple enough gameplay that my wife enjoys joining in.
Crash Team Racing Nitro Fueled - They really did a good job maintaining the feel of the original while making everything look fantastic. I was worried going into it that the game play would feel different (which would be a huge let down because the original CTR is the best cart game ever made)
Tony Hawk's Pro Skater 1&2 - They did a great job combining the games to make it seem like 1. Gets a little repetitive once you start playing through the game multiple times with the different skaters. I mean who really wants to play thru the thing 20 times?
Horizon Zero Dawn - Beautiful game. Kinda struggling getting used to the controls, but after some practice I'm sure it'll be fine.
God of War - Wow. Gorgeous, fun to explore, great world building storyline, tons of side quests, a lot of equipment customization to suit your play style. I'm about half way through this one and I love it.
And there are tons more that I'd like to get to from that gen. Red Dead, Spiderman, The Last of Us Part 2, Ghost of Tsushima, Uncharted 4, and many others.
So, judging strictly from the library I'd call it a solid platform. I can't speak to the performance of the system though, but the games look and run great on a PS5. lol
That said, I'll give it an 8/10