Butler showed great foot speed, hip flexibility, and most importantly competitive spirit. Even when he didn't get the best jam or didn't have the best coverage, he was able to fight his way back into position and show off his athletic ability. Obviously there are still kinks in his game that need to be expected witha second year, undrafted rookie, but the progress that he has shown over the past year is impressive and there is no reason to think that a player with his work ethic will not continue to improve.
Butler isn't the only way to fix what was a vaunted secondary a year ago, but he certainly seems to be one of the best tools to do the job. With a lot of young corners on the roster, look for Coach Belichick to use Butler as an example of what it takes to move up a roster and make an impact on a Super Bowl winning team. Then again, the coach may use him as an example to make sure nobody's ego beomes too big to manage!
What I saw from Butler was very promising and I look forward to his continued development as the preseason wears on.