I've been playing a lot of Returnal lately and one aspect I really appreciate is how the game cold boots into gameplay within a few seconds of launching it. It may be even faster if you use the game cards for specific events, but I haven't tried those for this title yet. The same is true for several next gen only titles on the PS5.
I have used the title cards on Astro's Playroom and Demon's Souls and appreciated how quickly I was able to jump into various areas even if the game wasn't in a suspended state.
The same is true for notifications of friends' activity. When someone from my friends list beats one of my scores in Astro's Playroom or Sackboy, I'm able to jump into that particular event and try to regain the lead, actually playing the game in less than 5 seconds. It's already created a fun and engaging back and forth with a few friends as we compete and trash talk each other with rapid feedback.
This is all possible due to the confluence of the design of the OS, the SSD, and in some cases the lack of title screens.
Games like GTA have skipped the title screen for several generations now, preferring to load your most recent progress, but the speed of loading and the ability to jump into specific areas directly is game changing. With GTA, even if I got a notification that something was going on in game, I wouldn't necessarily switch right away because of the time cost it would incur.
To me this functionality, powered by the SSD and console throughput, has the potential to be my personal definition of "next gen".
Cross gen titles are definitely held back in this regard. Or I should say that, to my knowledge, all cross gen titles have some form of loading screen. This is true of Sackboy, Spiderman MM, etc, even if they are much much faster.
People talk about resolution, ray tracing, frame rate, etc all the time for these next gen titles, but not having to wait to load is so amazing.