I grabbed one for $5.29.
The two quarter-pound patties appear to be the same as you'd find in a Whopper, which basically means they're wide and pretty thin as far as burger patties go. This means they're not likely to be very juicy and they weren't. There were some nice grill marks on the patties but, oddly, none of the smoky flavor you'd expect from them. I think the burger would have been better served by a thicker patty like they used to have with the similar (and superior) A.1. Steakhouse XT.
I think someone goof as mine came with some sort of white cheese. I'm guessing it's Swiss from the Mushroom & Swiss Big King. It was mild and creamy.
Overall, Burger King's A.1. Ultimate Cheeseburger went a little too heavy on the A.1. to the detriment of everything else. It's also really pricey for what you get. I liked that it was fairly simple though, but you might want to ask for the sauce on the side if you're looking to try it.
Nutritional Info - Burger King A.1. Ultimate Cheeseburger
Calories - 850 (from Fat - 460)
Fat - 51g (Saturated Fat - 22g)
Sodium - 1480mg
Carbs - 43g (Sugar - 8g)
Protein - 41g