Leonardo DiCaprio delivered a strong and intense performance. He definitely gave it all at full throttle. Brad Pitt was genuinely comfortable at providing Leo the support he needed so that he could shine through.
In other words, Brad, being Brad, was enough to keep the pace and interest in the plot.
The ending was somewhat unexpected, although it seems to me that Tarantino really embraced and cared for the film. It is clear that he feels bothered and disturbed by the tragic event that culminated in Sharon Tate's death. I applaud Tarantino's attempt to bring some sense of justice to that, if those horrible moments had never taken place.