Take Best of the new design not all
I liked the left column, top bar, colors. Even the organization of emails is pretty good, however with showing photos in emails - number of email visible have decreased, so there should be an option to turn it on or off.
Chain of email option is good, however it should also be 1 click on- off. Sometimes it makes it difficult to navigate. Outlook is known for its cleanliness. In this version some things are better but overall it is compromising on its cleanliness solid point.