My first thought is that, although I appreciate the added functionality, the app does not feel like a native macOS application anymore. The buttons, the icons, the menus... they all seem to resemble the Windows user interface instead. An additional element in which this is shown, is the sidebar: the previous app had a slightly translucent sidebar, while it's completely opaque in Enpass 6.
I'd imagine these changes are the consequences of trying to ease the process of developing for different platforms. For me, however, this might be a reason to switch to another password manager: the UI simply doesn't do it for me.