Having done a few playthroughs here are some thoughts on Act 3.
Act 3 should have been split into 3 parts, act 3 could have been kill one of the two, Act 4 kill the other, Act 5 kill the 'Absolute' (with the side quests still being available up to the end of Act 4)
Breaking it down like this would have fitted the way the narrative developed in Act 2 where you killing the other one draws it to a close. This would have also presented the opportunity for the game to make more of the fact that you've killed the other big baddies e.g. a campfire scene similar to the Grove one. At the moment killing one of the other two feels like it has the same impact on your party as finding out what's been eating the pigeons. Also the big companion choices feel somewhat underplayed - oh and for gods sake let us hug Shadow during her scene.
Separate Acts would also have lead to more 'romance' interactions as it currently feels like the all important bond you build with another character is almost forgotten in Act 3. The romance interactions wouldn't, of course, need to be scenes of intimacy but they could show the ever growing bond.
Another advantage would be that the 3rd act wouldn't feel quite as sprawling.
