I came here after reading the post on reddit about the cut content, I was rather annoyed at Larians statements not turning out to be true especially regarding Act 2's Length and the Upper City.
Some noteable things that were cut - Avernus as an explorable zone - Upper City - Story content for Minthara, Halsin and Karlach, Karlach really drew the short straw - Ethel's Covern were supposed to appear in Act 2 + 3 - Bhaal and Orin versus the Creche (You could choose sides) - You could pick certain evil deities as a cleric and get unique dialogue options
That's just some of the stuff that was cut the list is much much longer and as someone mentioned on page 1 " The Larian final act curse strikes again " those of us who played DOS2 knew this already and it was eventually addressed with the DE so I'm hoping that they don't forget Avernus, Upper City and more content for the companions.