I've been with them for a couple of years too and I use all their services (mail, calendar, drive, VPN, pass and simplelogin) but calling it flawless is a bit of an overstatement.
Their outside communication is nonexistent at best, development speed is unbearably slow and Linux support, the most privacy countious user-base?, is lacking a lot.
Hopefully in the next couple years they sinally manage to release contact sync and a Linux client for Drive.