I saw part one minutes ago. As someone to whom Grandmaster Flash and the likes of him is a big part of growing up the movie strikes a cord with me by nature.
But apart from that I like the wild mixture of dance movie, musical, Hip Hop party, poetry slam, documentary, Kungfu flick, coming of age, spraying, "mastering" the ceremony, DJing, comedy, drama and romance. I recommend to watch the documentary Rumble Kings before watching The Get Down to fetch some historical background information.
Hip Hop with its sampling, mixing, scratching and juggling with words opened up a musical playground for audience and artists. The movie transforms this successfully into visuals.