I go to Vegas at least once a month and see at least 3 or 4 shows every trip.  I have seen every Cirque show, and while Le Reve is not a Cirque show, it is very Cirque-like (Franco Dragon, the director of Le REve, directed O and other CIrque shows).  Quite simply is it one of the most beautiful shows I have ever seen.  The cast is energetic, talented and beautiful, the theater is astounding and there are moments of shear visual magic.  I have seen Le Reve four times now and will see it again (I brought a group of 15 people to see it this past June, and 5 of them have been back to see it again).  If you want to spend 75 minutes watching something beautiful, go see Le Reve.  Tickets are steep ($125), but I always feel like I get my money's worth.  Also, keep your eyes open for the guy who slams himself around in the stage in an inch of water; I'v enever seen anythng like it before.