Seems the most interesting "data" on it are mileage, power, price.
20mpg EPA highway
403HP
$41k
Similiarly equipped Tundra (crewcab SB 4x4/AWD):
18mpg EPA highway
381HP
$41K
The Tundra has nearly a 2,000lb rated tow advantage, but both have the same payload. If you have 4 adults, a full tank, and typical gear in the bed, tongue weight becomes the limiter, not rated tow capacity. Honestly, when you are towing over 8000lb a lot, perhaps neither truck is a good fit.
The engine in the Denali is the LSx family engine which is the new "Small Block Chevy" that debuted in 1997 and comes in flavors from 4.8L to 7.0L. It is a deceptively simple design with only 2 valves per cylinder and pushrods. But it has one of the best brake specific fuel consumption numbers in the gasoline industry. Even the 505HP version of the engine does not get the gas-guzzler tax (Corvette - 27mpg). There is a 650HP version in test mules that will be available in 2008 which is testing at 26mpg.