For a Tarantino movie, this really lagged. They could easily have cut an hour and still have had an (arguably more so) enjoyable film. This feels like little more than a nostalgia piece with 10 minutes of classic Tarantino violence tagged onto the end.
The attention to detail is amazing in recreating the time period, and to be sure there are some great performances from the actors involved. But be prepared to spend 2 hours wondering what this movie is really about - only to find out that it's a pretty unremarkable "if only ___ had had happened" ending.
If you live the '60's, it's a must see. Any otherwise, at least wait until it's available on DVD or streaming so you can use your phone for entertainment to get you through the slow bits....