What do you like best?
Protonmail really convinced me for its security features because it does encryption and two step login. They claim that they do not save the second password on their databases which is nice. Also you can send an email with encryption and only your receiver can read that message if she/he knows the decryption password. Also the interface is very easy to use and mobile application is also very smooth and useful which is so nice for me.
What do you dislike?
If you lost the second login password, it means that you lost the account completely because they do not save that password so it can be a problem for some people. It would be great if it works offline I mean you cant read your mails if you are offline.
User interface is easy to use however it seems like they bought a free template from template sites and use it directly. I think they should change it to better appearance.
Recommendations to others considering the product
I recommend protonmail for everyone who wants to send secured e mail and keep top secret information in there. They claim that their servers in switzerland so I believe that they are trustable and useful for everyone.
What business problems are you solving with the product? What benefits have you realized?
I am using protonmail for my very important business emails etc. It gives me trust and makes me feel more secured.