I would call Bush a very flashy and impressively athletic football player. I would not call him a beast. He is not the most dominant RB in the NCAA right now, he may be the most overall athletic player and a good RB, but he is not the best RB in the NCAA, much less in the last 20 years or whatever some people are claiming. He will likely be a Warrick Dunn-type RB, very fast and quick but not very big and not going to run over anyone. Dunn has developed a decent ability to run up the middle which I do not yet see in Bush, but he can develop that with time. As for Bush being in the top 5 in ypc, I seriously doubt that. Dunn for instance has had some very impressive seasons and some below-average seasons. When he had good blocking, he's excelled (5.2 ypc this year, 4.6 in 2000, 4.2 in 1998, 4.4 in 1997) but when the blocking hasn't been so good, he's looked really bad (3.2 ypc in 1999, 2.8 ypc in 2001), and I see Bush having the same tendencies. If he has a great OL in front of him, he could consistently average 4.7-5.2 yards per carry each season, but if he doesn't have great blockers (like we are now and will be for a couple years if we don't address the situation now) he will probably be more in the 3.6-4.1 yards per carry range. The most carries Dunn has ever had in a season was 265 last year (16.6 carries per game), for that matter the most touches he's had in a season (carries + catches) is 294 (18.4 touches per game), and that's about all I see Bush getting. I for one am not willing to spend $50 million and give up three or four additional draft picks for that kind of production.
Adrian Peterson is a more dominant RB than Reggie Bush. Bush may be a more talented overall player, but Peterson is the better pure RB. Peterson had possibly the best freshman season ever in the NCAA by a RB. When Peterson had a team full of studs like Bush currently has, he posted 1925 rushing yards (5.7 ypc) and 15 TDs, and that as a true freshman. He beat out Cedric Benson in rushing that year, the same Cedric Benson that was the #4 pick in this year's draft, and Peterson was a freshman while Benson was a senior. Comparing Bush to Peterson this year is not a great comparison because Peterson lost half the starters on his team and was left as the only weapon and he was injured for a decent portion of the year. That said, Peterson put up better rushing numbers as a freshman than Bush has done as a junior when the two had comparable teams around them, so I would call him a more dominant RB, not to mention he is a much more physical runner. Bush is still a better athlete and likely a better all-round player, but Peterson is the superior RB.