The generally quality documentary series "The History of Rock & Roll" really hits a roadblock with the eighth installment, "The 70's - Have a Nice Day". The musical landscape of the 1970's saw music branching out into many disparate styles as well as the extreme popularity of the disingenuous, overly calculated disco genre. Many styles are discussed during the episode's hour long format, some of which are less "rock" than others and certain artists are over explored, while others are ignored or barely mentioned. This segment feels particularly slapdash, and clearly wanting to be given the multi-installment treatment of the sixties music, which was represented in some way by a staggering seven. There's a lot of quality music, historical information, and artist given commentary to make this worthwhile viewing, but a music fan who understands the importance of the music from that era recognizes the missing chunks of information.