In responding to the ASA, Motorola said that the claim on the ads did not have to do with processor speed. The Schaumburg based manufacturer added that while the ATRIX has a slower processor than the Galaxy S II, the latter device could not operate the unique computer-like accessories that the ATRIX offers. Motorola said that it never claimed that its phone has the fastest processor but instead was talking about the the features, performance and capabilities of its device.
The U.K. Advertising Standards Agency said that they felt that viewers would be thinking about processing speed when hearing Motorola's claim about the ATRIX being the world's most powerful smartphone, not whether a phone had a dock that turns it into a Laptop computer or a media center. As the ASA said in a statement, "Because the Samsung Galaxy S II i9100 had a faster processor than the ATRIX, we considered the claim "The world's most powerful smartphone" had not been substantiated by comparative evidence and concluded that it was misleading." You can see one of the now banned ads by clicking on the video below.
source: TheTelegraph via AndroidCentral