I think their services are generally pretty good, yes.

But their frontends really aren't. Their web apps are serviceable for desktop use. The Proton Mail desktop app is essentially the web app in an Electron or CEF wrapper. But on the desktop you can at least use Proton Bridge to then use whatever IMAP mail client you want.

On mobile, you can't. You have to use their services with the corresponding app they provide on Android and iOS. I moved from iCloud Mail to Proton just a few weeks ago (and I also had Proton a few years ago), which meant I had to switch from the default iOS "Mail" app to the Proton Mail app, as Proton doesn't support IMAP without a bridge (naturally, as IMAP doesn't support end-to-end encryption).

Unfortunately the Proton Mail app is not a fully native app but instead it must be using React Native or something similar. It's a low effort port of the web app, meaning very few integrations with iOS were actually done. For example, Apple Mail can show the email content in the notification, Proton Mail doesn't. At least you can mark mails as read in the notification, but you can only see the subject line without opening the app. Offline functionality is very limited as mail contents aren't cached on device, which can also make opening specific mails very slow (comparatively at least), and overall the app just feels less responsive compared to a native Swift UI app. UI animations aren't "attached to your finger", instead they just fully play once triggered no matter what. Calendar attachments just show up as an .ics file that you then have to download and open to add them to your calendar instead of just having a simple "Add to calendar" button.

But the worst part is that the iPad version is basically just the iPhone version blown up to fill the screen. It doesn't have a multi-column layout with your inbox on the left and the selected mail on the right. Nope, just like on the phone app, you open a single mail, it takes over the whole screen and you have to go back to your inbox again.

For that reason I didn't even bother with their calendar service.

The VPN app is fine. The iPad app is the same blown up iPhone app as well, but you don't actively use the app for more than a few seconds to pick and connect to a server, so I don't care.

Proton Pass is a little bit better (it's also newer I think), it does have a separate iPad layout. It also integrates well with their email alias service (SimpleLogin, although the SimpleLogin service standalone is a bit different still). I still use 1Password though because of the SSH Agent integration on desktop and it also comes with a Safari iOS browser extension for additional convenience features over just the native OS integration for password managers.

I actually use SimpleLogin and while it's technically not an OG Proton service, you do get their Premium service included with your Proton subscription (Proton owns SimpleLogin now). Very good service and hey, it has a pretty solid iOS app.

I didn't really use Proton Drive yet, but I'll probably use it for archiving some stuff by just uploading it through the web interface. Last time I checked they didn't have a native Linux client yet (for Dropbox-like folder sync), but somebody hacked support into rclone I think, although the API isn't documented on Proton's part, so it's probably not super-reliable.

That's it, right? Apparently Proton might acquire Simple Notes, and I'd sure take that included in my subscription, although I feel like Proton should focus on vastly improving their existing services first before they broaden their portfolio.