First problem for common Internet user is with the Avatar croper (difficulty to select the square from a border of the image). Some labels (fields names) are not clear and are adding confusion, too many options in some features (for example: position of borders in the profile customizer...), undiscoverable link to some feature (for example: Customize button in Actions menu block rather than in Profile menu or features placed under Dashboard rather than in Profile submenu), design of some page (especially see more Profile page - infos, medias,... that belong to the profile have to be developed), some quick links are missing to browser from one page to another without to have to use the navigation menu ever time..., floating menu that overlap the bottom menu, "Your Status Message" or buttons like "Create Event" that overlap menu options,...

Andrew, why not try to ask some of your friends who are not programmers to browser Dolphin, give them some tasks to do... and see the problems they will encounter ???
Lot of common Internet users don't share your logic, are lost in front of pages with so many options...

... From main menu, People - All Memmbers: in the block By Country, countries are displayed in random order (could be in alphabetical order) and international codes are used rather than the full name of the county... Number of countries (flag + code) are not identifiable.
And this long list is really ugly :-)