Well seems that the topic I mentioned here just a little earlier, Brand Attack on the Rise, was took over as a main subject on brand guru Laura Ries’s Blog, in a post on how and when a brand shoul attack.
In general, the leader should never attack or name the competition. Instead the leader should promote the category. By attacking a competitor or responding to an attack ad, the leader only legitimizes the competition and the existence of a choice. Neither is good.
If under attack, a leader should instead address any problems with PR. Never with advertising. When Apple says consumers are frustrated with Vista in its advertising, Microsoft shouldn’t run ads saying everybody loves Vista.
That above, is just a quote. More, with examples and details on Ries’s blog here.