I doubt Griffin will be an olowokandi type bust, but i think he's far from a sure thing superstar either. I think he was seen as the consensus #1 in what was regarded as a pretty weak draft. It' a big surprise how deep the draft has been, and most of that quality is actually in guards, and is more depth in quality starters than superstars. Remember that when in doubt, bigs get drafted over smalls, so that's pretty much how he ended up #1: he was a big guy with the fewest question marks. But looking at the rookies this year, it's not as if he had to beat out a lot of great big guys...i mean, the most impressive big in this year's class is probably Blair, who went in the second round because he literally has no meniscus in his knees. So he could easily end up being a solid starter, and not a superstar 20-10 guy.
Also keep in mind that Favors is a freshman and Griffin came out after his sophomore year, and Griffin's sophomore stats were much better than his freshman stats. If you compare freshman years, they're pretty comprable:
----------Min----PPG--RPG--APG---TO---FG%--FT%--BPG-STPG-PPS
Griffin: 28.4--14.7--9.1--1.8--2.3--.568--.589--.8--1.0--1.49
Favors: 27.5--12.4--8.4--1.0--2.5--.611--.629--2.1--.9--1.53
So similar minutes, Favors slightly fewer points, rebounds, and assists, but noticeably more efficient on offense. (this may be key considering one major criticism of georgia tech was that their guards were terrible and didn't get the ball to the bigs). One thing that stands out to me is the blocks per game: .8 for blake compared to 2.1 for Favors. This could be quite indicative of a major athletic advantage for Favors, that could lead to more success in the NBA, when everyone is an elite athlete.