Wanted to experience this service, as I'm accustomed to purchasing tix way in advance for shows. We did get discounted tickets for KA.
The only issues is that you have to wait in line to purchase discounted vouchers. Then after purchasing the vouchers, you have to trek to the box office for the actual tix. This whole process took us 1-1 1/2 hours, which could have been spent doing other activities. Luckily, this is considered a non-peak time that we went, so therefore, the lines were shorter than usual.
Tip: Although there are various locations on the strip, you have to search for the locations with the shorter lines. The location by the Coke bottle is super busy. We walked a block down to another location and the line was much shorter.