I don't think it is a bad pick. I actually think the Vikings may pick him at 3 or 4. Many people like him. As I learn more about him, I am liking him more and more.
I am playing in a Mock Draft on the Vikings site in three weeks and my two teams are Giants and Titans. One of those I am considering for the Giant is McCaffrey. So, while I called it a reach, I think it is a move that the Giants may make. He also has the demeanor/personality of Giants QBs, like Eli and Daniel Jones.
It is a good pick for the Giants.