I was, actually. We went for my birthday, Jan 2, so we arrived toward the end of December and stayed for 10 days, bouncing between Tokyo, Kyoto and Osaka. I will say, if you're planning to visit for NYE, locals don't traditionally celebrate the way people do in the US (not sure where you originate). There are, however, places that cater to those who want to party and stay up all night, many of them seemed to be clubs. We didn't do that. Also, many shops shut down for 2-3 days around NYE. Anyway, I can't wait to go back, such a cool place.