There's no such thing as a can't-miss prospect, but Andrew Luck has everything you're looking for in a quarterback. In terms of physical tools, he has a prototypical frame, strong arm and above-average pocket mobility.
In terms of his football intelligence, he has a strong understanding of how to run an offense and he makes sound decisions on the field. Finally, there's no question about his ability to step into an NFL huddle and take charge of it.
This appears to be a perfect fit of a quarterback's skill set with the Colts' new offensive philosophy. Offensive coordinator Bruce Arians will run a Pittsburgh-style scheme with a lot of bunch formations and movement and some no-huddle. Luck will have a lot of freedom to audible at the line of scrimmage. They want to be a much more run-oriented offense which could set up good play action, which is Luck's strength. This is a perfect offense for him, it's just a shame he won't have a better supporting cast in the beginning.
The two things that set RG3 and Luck apart are concerns about RG3's durability and how long it will take for him to transition to more of a pro-style offense. While there are concerns about the pro-style offense, he's done it enough in college that you know he'll be successful in the NFL.
If Luck is 1, then RG3 is 1A. In fact, he has an even stronger arm and he moves just as well. If he stays healthy, he'll be the quarterback Washington so desperately needed and well worth the picks they gave up to get him.
He is a perfect guy to run Mike Shanahan's offense, which is a strong zone-blocking run game and a passing game that wants the QB to roll out, throw a lot of bootlegs and motion some off play action and that leads to a lot of half-field reads and scrambles, which fits RG3 perfectly. They will also use a lot of motions and shifts and multi-receiver packages to give him a lot of options in the passing game. He will always be a threat to tuck the ball and run. They worked hard to give him a supporting cast in free agency.