I just watched the finish. Gavaria sprint was Cavendish-like in his prime! His speed compared to everyone else was remarkable. Very impressive considering the distance he traveled, the ground he made up so quickly. It was awesome to behold.
Gaviria had a huge gap to cover, but still managed to close the gap and win, that's pretty impressive!!!
To discuss he is the best, the second or the third sprinter in the world at this moment is nonsense, he is the best sprinter in Giro 2017 (with a huge margin over the second one and this is still his first GT), this sprint was enormous and he deserves respect for it, he made history on his first Giro, he deserves massive kudos for that, but history needs to be written and time will tell.
He can be classified as a tier A sprinter ATM, he is one of the best, period!