It's true that Sen. Clinton's security attack ad echoes Republican efforts. But on two fronts, I think it fails:
1) It's not a very good ad. It's, like most of the ads authorized by Clinton and Penn, generic to the point of banality. My first impression on watching it, with the family sleeping and the phone ringing n the background is that someone should pick up the freaking phone!
2) America is so over this crap. The time when politicians, especially Republicans, can scare up votes by screaming OMG TEH TERRORISTS ARE COMING FOR YOUR BABIES UNLESS YOU VOTE FOR US AND GIVE US THE RIGHT TO SUBPOENA YOUR HIGH SCHOOL ATTENDANCE RECORDS is over. The Republican party got a leg up politically by using the boogeyman device, but they've used it one time too many. People are aware of the terror threat and want it destroyed but they understand now that hiding under the covers and voting for the candidate who makes you pee your pants in fear isn't going to produce a solution. In many ways, the people have grown up -- ahead of the politicians.
2a) This isn't really a "Daisy" ad. The actual "Daisy" ad is good and effective, and unlike this generic ad produced a stark contrast between LBJ and the lunacy of what Goldwater was pushing.
Hillary Clinton is echoing the failing Republican message, and their ads this fall are likely to echo this tired old theme. It's why their chances are slim.
UPDATE: Here's Obama's response ad.