I had a bad experience upgrading from SmarterMail 15.5.6222 to 16.1.6418. The new visual is really nice with a beautiful front-end using Angular. However some issues forced me to roll back to the previous 15x:

 

1) The new interface is SLOW and doesn’t seems to work properly. For example in the administration panel, when I clicked on some link in the menu it takes several seconds to load. Another example, when I try to delete a message in the webmail using the “del” key nothing happens, however the message is gone only if I restart the page.

 

2) Several JavaScript bugs appeared in the Chrome Dev console. That is a sign that the front-end is broken.

 

3) I’ve tried to change the welcome text in the administration settings however a generic red error message is displayed on the bottom right corner.

 

4) The SmarterMail process looks like to use more RAM. About 50 MB or 80 MB more.

Fortunately I were able to fully restore the previous version from a backup. So I’ll stick with 15x for a while until those issues is fixed.