Vitality was good, Zywoo had his moments of strength and then some of stagnation, and if he wasn't carrying enough, his other teammates would fade. As you mentioned, it was a long final, lasting six hours.
Few people expected G2 to win, or even reach the final, perhaps only G2 fans, but they did.
The real question is whether G2 can win such big tournaments again, especially in the upcoming tournaments.