32-bit installer images are no longer provided for Ubuntu Desktop. The Ubuntu Desktop now uses GNOME instead of Unity. On supported systems, Wayland is now the default display server. The older display server is still available: just choose Ubuntu on Xorg from the cog on the log in screen. GDM has replaced LightDM as the default display manager. The login screen now uses virtual terminal 1 instead of virtual terminal…
Installing "gnome-session" should provide the default GNOME desktop (the default GNOME is a heavily modified one). I have not upgraded yet, so have not tried, but read on OMGUbuntu.