OP is looking to move away from Google. Immediately getting locked into a different, arguably more restrictive, platform isn't a solution.
Now in general:
Pros:
free (paid plan only?)
company will stay in business for a while
Cons:
subject to Apple's privacy policy
US based company, not great for privacy
locked into a different platform
Apple's walled garden ecosystem means long term use is questionable. Will Apple keep supporting 3rd party email clients in 1,3,5 years? Do they even support it now? Who knows?
Apple has control over your account. If they screw you over on an iPhone purchase and you do a credit card charge back on them (for any reason really) do they let you keep your account? Google doesn't
It is free and comes with 5GB of cloud storage. For $1 a month, you get 50GB of cloud, a personal domain, Private relay (basically built in VPN), and email relay (masks your email address when signing up for a site, site never gets your actual email address, apple receive an email at the masked address and forwards to you.)