If you're a fan of Elvis, you'll probably like this show whether its good or not. Its got everything you'd ever want in an Elvis show (and perhaps some things you don't want or understand, too).
My seats were in the front row of the balcony. I have to admit I was concerned about being so far away and up high, but with the size of the stage and some of the set pieces, I was happy we sat where we did. We could see everything from there.
The show is basically the life and times of Elvis, from his discovery to Vegas. The Colonel guides us through from beginning to end, working the crowd before the show starts by getting them to dance or sing for an Elvis button or picture. His mic went out a couple of times during this "preview" performance (shows put on before grand opening so they can work out the kinks).
The acts were varied from obvious choices to some weird stuff. I could, for the most part, follow along even when it was a bit strange (i.e. realize what they were trying to get across), but I can see how a lot of people may not get the ideas being presented. I have seen KA, O and Believe and Viva Elvis is within the vein of these shows but does make its own mark. My friend said that Viva Elvis was not as good as LOVE (but he is a huge Beatles fan, too).
I would still recommend going to see KA, O or a non-Cirque but Cirquey "Le Reve" before seeing Viva Elvis. I did like Viva Elvis, a lot, but for the amount of money being spent on a ticket with the probability you'll be far away from the stage, you can get more bang for your buck with the better KA and O, or spend the same amount of money and be at the maximum 13 rows from stage/water in Le Reve.
Either way, if you see any of these shows, you'll have a good time.