Aside from the Steel Watch Factory, and Gondian Prisoners I enjoyed Act III. Lots of cool stuff and it was fun to complete the companion quests. I agree with the issues around pacing but feel the developers were caught between a choice of; A) more logical pacing and less Act III content or B) more content and illogical pacing. I'm glad they made Act III as large as it is.
As far as the Emperor ...meh it's fine. Larian isn't the first storyteller to have trouble creating a memorable ending.