Because it got cancelled means it can't be worth watching?
It was no 24, but it's not a bad way to kill a sick day.
I didn't watch The Event, so I don't know how series-arc focused it was, but in general it can be very frustrating to watch a show completely driven by a series-long storyline if it gets canceled prematurely. Often the sole reason people watch such shows is for the plotline that's supposed to runs throughout the show till its completion. If they don't get the chance to finish the story because the get canceled, it can be very unsatisfying.
Of course there have been plenty of show that got the chance to wrap up and people hated the endings, but at least you get to see where it all goes.