Sidebar hardcoded
Right now there is no way to edit anything in the sidebar. I can't add or remove items from the builtin places. The only way to add things is with the very limited bookmarks. This not very ideal, since people have different kinds of bookmarks like network, regular folders (not drives because those are gone too now, with no way of adding them back) and its very unintuitive to have them all in the same section. I understand that some of these decisions were done for the sake of user friendliness but i don't think having no customizabilty is the way to go.
I would suggest maybe something closer to what Dolphin has, like being able to add your own entries to any section and hide places you don't care about. Also with this sections would also need a clearer distinction in each section so users know what is what.