if you're in residence then ive heard it can be a good way to connect with people and have a loud, rowdy, party-type time.
If you're off-campus, then its not as great as it is for residence ppl (from what ive heard). but still quite fun if u go to events that are open to all or are off-campus events.
If you commute (like me) then it might probably be even less fun.
As for macpass (or whatever they call it now) I personally found that to be over-rated and a waste of money. I made good friends over the course of time in my first year and not in frosh week. The people i came to know in frosh week just faded away because we had diff programs or faculties and hardly met each other after W.W.
Welcome week does give u your very first chance to have fun at Mac but having fun is not just restricted to welcome week, u can party whenever u want