There are some artistic pieces like Mosaic, deep, Zelda like RPG's like Oceanhorn 2, fun but extensive casual games like What the Golf, mistery puzzle solving ones like Discolored, exciting racing titles like Super Impossible, all of which have outstanding quality, no in-app transactions or advertisements, and are well worth 4.99 by themselves. I would say, you can find about 10% of games in the catalog are worth 9.99 or more, 40% around 4.99, and about 50% worth 0.99.
Now there's a quality threshold in the sense that even if the genre or style of a specific game might not be your cup of tea, none of the games in Arcade are crap, they are well-made, even if at times simple, experiences. Yes, sans a couple exceptions, these are not full blown AAA $60 titles. Then again, this service costs 4.99 a month for dozens of very inmersive titles.
PRO TIP: If you dont own a compatible gamepad yet, do buy yourself a dualshock or an xbox controller, also, if you dont own an Apple TV, with an adaptor you can hook your iPhone or iPad to your TV and with the gamepad you got yourself a game console. There are games outside of Apple Arcade, like Real Racing 3 and Fortnite which can be play hooked up to a TV and with a gamepad as well.
For me Apple Arcade pushed me to buy a Dualshock 4 controller, and after a few years off Im back to gaming again.