I always wondered what the large blue and yellow tent was near SBC/Pac Bell Park, and now I know. We spent our New Year's Eve inside that tent watching Cirque du Soleil's Corteo, which is a "a festive parade imagined by a clown." Unlike everyone else I went with, I don't have prior Cirque shows to compare against. I did go to Teatro Zinzanni this month for a company holiday party, which was a fun acrobatic dinner theater experience, but the scale and type of entertainment was entirely different. Zinzanni is a fun way to watch some impressive individual juggling and acrobatics up close, while also seeing your bosses used as embarrassing props. Corteo is a barrage of acrobatic performance, with people spinning up into the air on chandeliers, combined trapeze and trampoline, and humans turned into spinning discs inside of cyr rings.
It was impressive and had thumbs up from everyone I went with. It didn't get a #1 Cirque show rating -- d preferred La Nouba at Disney World and Jed preferred Varekai. The common complaint was that the acts each started with a bang but ended comparatively weakly -- they didn't save the best for last.
The remaining San Francisco shows are probably sold out, but you should be able to see it in San Jose if you're interested (Corteo tickets).