They are more secure than password authentication, though how much more secure depends on how the user manages their passwords.

If a user never reuses passwords across different services and maintains long complex passwords, preferably randomized strings; the security upgrade of Passkeys is quite marginal. Arguably marginal enough to not even bother. The farther a user gets from 'ideal' password security practices though, the more of a security upgrade Passkeys would be for them; though convincing them of that is another story...

Switching to Passkeys does take a lot of responsibility off of both the user and service provider. The user no longer needs to ensure passwords aren't reused, insufficiently complex, or already compromised; and the service provider doesn't need to worry about leaking your passkey as they only have the public key portion which can't be used to login as you.

In some ways they can be more inconvenient though. With a password, even long unique complex passwords stored in my password manager; I can open the password manager on my phone, read the password I want, and manually enter it into an unfamiliar or shared device without having to load my entire password/key vault onto that device. Passkeys make that impossible; essentially forcing you provide the whole vault to the device or give up. It is also a big step for people that aren't familiar with password managers and are used to just remembering their passwords, to then switch to a passkey manager where they can't use their memory to login anymore.

There's good sides and bad sides to everything really. Some people will prefer one way, some will want the other way. Ultimately I think we'll get pushed into using Passkeys by most companies, just so they can shed some of the responsibility of keeping your credentials secure. A stolen passkey database, unlike a password database, would not allow you to pose as users, which leads to less claims of fraudulent activity.