Unfortunately, Woodstock is widely considered a god-awful performance by the Dead. They dropped acid just before their set (not too uncommon), had equipment issues, and played over their allotted time.
John Fogerty of CCR didn't appreciate it very much as he had to follow them, and later commented that by the time he took the stage, "the Grateful Dead had put 500,000 people to sleep."
The Dead's set was so unremarkable that it was cut from the Woodstock album and film. Oh well, they can't all be winners, right? @porcupine48 I'm sure there's an opportunity for a joke here.