Finally saw this and nice to see a good discussion here.
Re: the violence against the women at the end. I found the head smashing gratuitous in a stupid and aggravating way (much like the final shootout in Django), but overall the extreme violence perpetrated by Cliff and his dog on the Manson Family members felt earned and cathartic. Tarantino relies on viewers having some familiarity with the murder of Sharon Tate. I've been working on a documentary series about the Manson Family the last few months, so I'm now more than familiar with the people and events involved.
Tarantino's finale is a direct response to the real life violence Tex Watson, Susan Atkins, and Patricia Krenwinkle inflicted on Sharon Tate and her friends. Steven Parent was shot three times and stabbed. Jay Sebring was shot and then stabbed seven times. Voytek Frykowski was shot, his head smashed in with the butt of the gun, and stabbed 51 times. Abigail Folger was stabbed 29 times. Sharon Tate, who was eight and a half months pregnant, was stabbed 16 times. Go ahead and Google the crime scene photographs.
The fairy tale ending worked for me. The final shot of Sharon, Abigail, and Voytek emerging from the house to join Jay and Rick like the happy ghosts of an impossible future was incredibly touching.
Somehow the ending really worked for me while the rest of the film didn't. I found it easy to watch, and some scenes were very good, but nothing particularly grabbed me. The Bruce Lee scene was cringe-inducingly bad.