First off, this film wasn't racial propaganda. Spike was shedding light on some of the racism encountered by black servicemen during World War 2, and how the contributions of black servicemen, in particular, but all minorities who fought in the military during that war have been minimized or outright forgotten, isn't propaganda. I give Spike credit for at least trying to make a movie about that oft-forgotten or respected contribution.
As for the movie itself, it's far from perfect. I thought the action scenes were better than I expected from Spike. The black soldiers mainly felt a bit war movie cliche, but were well acted. I didn't quite know what to make of the lovable dolt Train. He wasn't funny to me, nor did I really warm to his relationship with the young boy.
I'm not sure what 'miracles' the movie was referring to, and the final battle in the film ended with a huge WTF for me. I don't want to give away too much. But for the most I enjoyed the film.
Except for the very end. There was a character there that didn't fit, and it annoyed me. But I've often felt that Spike's movies usually fail to tell a coherent story, for him the journey or whatever message he wants to convey seem more important. So, in that regard, I think he got his point across. I just wished he had done it in a more straightup film, perhaps surrounding a real engagement during the war.