I liked the movie but something didn't grab me so it kept it from being great for me. I think I liked it more after I described it to someone that would never watch it, and I got more joy out of explaining it and enjoying the funny moments even more.
It could easily have been shorted and tightened up so I think that criticism is legitimate.
He did a good job at catching the vibe at that time and the look of it too.
The whole Sharon Tate and Manson stuff was like 2% of the movie and almost a McGuffin, but yes obviously it was needed to set up the ending which yes I really liked and wish it was real and not fictional. Totally predictable ending though. Of course not in the specifics like the dog food and dog and flame thrower but the trailer and it being a QT gave away that the murders at the house were not going to happen
So overall, it is an enjoyable film that for me, just missed being great. So I give it probably a B