I've seen a number of the Cirque shows in Vegas (as well as the Cirque-like Le Reve at the Wynn). Zarkana is very good. It brings together the trademark artistry, physicality, and precision of Cirque shows. The performers are amazing.
In general approach, the (I read) revamped Zarkana is probably most like a latter-day Mystere. No particular theme and relative emphasis on the clowns, but adding the impressive staging of more recent shows. Ka, from which this show borrows one of its more spectacular acts, is probably still my favorite Cirque performance in Vegas but this is still pretty darn good.