Colleague Tim Siglin released an extensive white paper today that assessed the affect of the Adobe Flash Player on the battery life of six Android powered devices and found that:
Flash Player 10.1 , in our initial tests, has negligible battery drain impact. Wi-Fi based use of Flash Player 10.1 in the native browser, with no other applications running, appears to use battery power consistent with that of non-Flash Player 10.1 content. Extended gaming play, while shortening the battery life, also does not appear to impact battery life any more than use of other highly interactive applications.
Flash-bashing has become somewhat of a national pastime, at least among the Apple/HTML5 crowd, but most negative claims are based on anecdotal evidence, or more often, pure unsubstantiated opinion. Tim’s extensive and balanced testing provides some facts that anyone on either side of the Flash argument should read. You can find the report here.