I think the biggest change for me is how quick I can switch between games. I don't know how much this is/was possible in previous generations on the 360/PS3 and the XOne and the PS4, but I can definitely say it was never this fast on the WiiU, Wii, and previous Nintendo generations. I've gone almost 100% digital this gen (another very big change) and part of the reason for that is simply that I don't want to get up to change the game I'm playing.
I love being able to switch between Animal Crossing: New Horizons, still a game I play daily, Rocket League, a game I play multiple times a day, as well as whichever main game I'm playing or trying out: currently Green Hell. I mean, how could I pass up picking this game up for les than $3.
Which brings me to another point: I have so many more games this gen. Granted, a ton of them are indie games or games I bought on sale, but boy am I going to be stoked if the Switch 2 allows me to keep my library, hopefully with bigger on board storage. One of these days I'll actually take the time to compare my libraries, but I'd be willing to bet that I've purchased twice as many games on Switch as I have on any other console.
The fact that the system boots up so quickly, and has a suspend feature, also means that in addition to playing more games at once, I'm playing more games, period. I can quickly jump into a game of Rocket League before work if I have 10-15 minutes to spare. I could take my Switch to work and finish a few shrines in BOTW in between customers.
Now, I'm not necessarily saying that all of these things are good changes. Being able to switch between games so quickly also means there are games I haven't played enough or gave up on too quickly. The allure of the Eshop with another game to try out is always there and skimming through the sales page is definitely a weekly if not daily ritual, always (slowly) cycling through the list to see if a hidden gem or a game that I've forgotten about has a sale price I just can't pass up.
Overall, though, I don't have many complaints with the changes, considering the real world situation. I love playing music, going to shows, having board game nights, etc, but in this current era those things just aren't as enticing. The Switch and the time I spend playing in the same room with my girlfriend (our tvs are stacked on top of each other) has made this maddening time just a little bit more tolerable.
Oh, and I definitely prefer cats!