I expect PS4-like performance in handheld mode and PS4-pro like performance in docked mode, albeit with a few more modern features. So I guess the end result will look slightly better than PS4 and PS4 Pro. And that's perfectly fine, Nintendo games will look great on the system.
As for other titles, since the Series S is a thing I expect most major games to run on Switch 2. If a game can run on Series S the devs should be able to make it run on Switch 2 with some sacrifices. (1080p@30fps vs 1440p@60fps / turn down graphical fidelity or whatever). That's fine. The only games that will struggle to run on the platform are absolutely massive (western) AAA games and there's only a handful of those every year.