I'm on their ~$50/year Standard Plan so that I can use it with my own domain names. I point my domains to FastMail's nameservers, and it automatically configures all email-related DNS settings. It can be setup to accept mail to arbitrary addresses, so I now use service.tld@my.tld when I create accounts on other websites, which can help with filtering or seeing who is leaking my info. Any other type of DNS record can be manually added, so I can still generally point my domains to my GitHub pages.
I can recall only one outage since I've been using the service. I use their web client and Android app (which is just a thin wrapper around the web client). They are not glamorous, but they are functional and feel snappy.
One thing to be aware of is that FastMail is based in Australia, which I believe has some backwards laws with respect to Internet privacy.
Not too worried. I only use email for signing up and all that. Not really a friend/family communication took anymore. Just want to get away from google.
I like the idea on the domain catch all because some sites won’t accept + anymore.
The one problem I've faced is my Fastmail email address ending up in the spam folder of friends and family and having to explain to them how to prevent that. I think that may be a leftover from the days when Fastmail offered free accounts. A bit annoying, but definitely not a deal breaker for me.
There have been some instances where both the fastmail domain and my business domain ended up in Spam for the receiver but that is less than a handful of times and I used Fastmail via Nodemailer as a proof of concept for a newsletter service so (ab)used the service without any issue.
ie:
Mobile client that does contacts/calendar/notes/drive
Mobile setup was really easy on iOS with a policy
Drive lets you host a static website or photo gallery
Custom domain catchall
Proton needs a bridge to use any client but theirs. DMARC/SPF/DKIM was a pretty easy setup for both. Proton is missing mobile clients for their new apps (drive/calendar). Its nice they give you another GB of storage a year, a VPN, and a bunch of the nolog/encryption niceties.