I've been going to Universal Studios both parks for many years in Jan and/or Feb. It was often empty and they would open half the park hours later after opening.
Beginning this year we got an annual pass for our 9 week stay during that time and we where amazed about how crowded it was compared to what we knew. Whatever time of the day we arrived or left there was a constant wait of 30 to 45 minutes for Minion Mayhem.
They are doing so much things right; great team members, fun themed food/drinks, new themed area's and awesome unique rides that deliver on the hype and then some more. They build Potter for the fans, not the pencil-pushers and it paid off, even the pencil-pushers must be happy.