I really love em client and the functionality of it as it simply just works BUT (there ́s always a but) it looks quite pale in comparision to outlook 2016 (see https://timedotcom.files.wordpress.com/2015/09/office-365-groups-in-outlook-2016.png?w=1680)
It looks very uninspiring and way too simple with the text only buttons and folders. My wish is to give us a choice to put a folder icon next to the inbox, sent, trash etc and then some icon to the email, calendar, contacts tab + some sexier looking buttons at top (new, update, reply etc). Heck if there would be an option for a similar look to outlook then I think you would make alot of ppl happy or just give us the possibility to make a theme with more customisation options.