Reviewers mostly see ProtonMail as a reliable, privacy-focused email service that is easy to use, with a smooth login experience and a cleaner interface than some mainstream alternatives. Several praise its end-to-end encryption and broader privacy tools. The main criticism is that the free plan feels too limited, with basic features like folders, rules, and some security options pushed behind a subscription. A few users also say Linux support is weak and that the service does not always work well with open standards.