Bad move, it looks evasive and since the press is swooning over the speech, they’ll be even more persistent to get her reaction:

Senator Hillary Rodham Clinton appeared at Philadelphia’s City Hall this afternoon, a few hours after Senator Barack Obama delivered a major speech on race not far from here. But despite the speech’s high profile and intense media coverage of it, Mrs. Clinton said at a news conference she had not heard it yet or read the text.
Many reporters muttered in disbelief during and after her remarks, surprised that a candidate as diligent as Mrs. Clinton -– who always talked about being well-prepared and doing her homework -– would not have read the speech yet. The fact that she was not prepared to comment on it, however, will keep the race issue alive for at least another news cycle, since reporters will keep seeking her reaction.