I was thinking about how this could have been done better.
The biggest problem, as I noted, was the feeling that Tarantino was trying to cram two movies into one with the "Revenge Drama" taking precedence despite the marketing focus on the more traditional "Action War Flick" of the Basterds. The Shosanna story DEFINITELY had a much different feel to it. The dark humor of the Basterds part of the story was gone, and it was definitely played much more seriously. Unfortunately, I don't think Tarantino has the chops for that type of story, so get rid of it. There's potential there, but leave it to someone who can REALLY do drama justice. As Shosanna's story is the central part of the ultimate, overall plot of the alternate history ending with the movie theater, that goes out the window, too.
Now once again, the marketing was making it look like a 21st Century take on The Dirty Dozen, so let's go with something more like that by focusing entirely on the Basterds themselves. Ok, so we have "Apache" Raine and his squad of Jewish-American GIs terrorizing German officers in Nazi-occupied Europe. Other than "killing Nat-zees" what would be the plot of the film? What would be the most poignant use of such characters? The Basterds ambush a top-ranking officer's convoy, and they discover evidence of a Death Camp within their area of operations. Honor-bound to protect their people, they decide to liberate the camp. The Basterds must figure out how to carry out the raid and escape with the prisoners back to Allied lines with their limited resources, ultimately putting their plan into action with a Dirty Dozen-style infiltration.
Simple, streamlined, to the point, action-packed. There's time to really learn about the characters, and an objective that will make the audience actually CARE if they succeed or fail. This could all still be done without sacrificing the black humor of the Basterds storyline from the movie as it was actually made.