I was very impressed - and I normally hate political speeches, even ones I agree with. I have never seen a better acceptance speech. He connected strong and extensive policy proposals and sharp but not vicious attacks on McCain to a base of common American values. He talked about every hotbutton issue in American politics - guns, gays, abortions, tax increases, and Iraq - without being offensive (or so it seemed to me - I agree more or less with him on all those issues so perhaps I'm not the best judge.) And he sounded like a real leader and fighter. It wasn't a typical Obama speech at all - much more specific and policy-oriented, and extremely direct - but the changes were very good for an acceptance speech. And the theatrics (stadium crowd, staging, fireworks) backed it all up well. The Republicans sounded shellshocked and I don't blame them. Actually I think everybody was shellshocked, because nobody was expecting this. It's just that Democrats were shellshocked and happy.
This is a very hard act for McCain to follow. In 2000, he would have been the right guy to present a similar policy platform from the center-right but his flipflopping over the past few years has damaged his credibility. Hitting the note of aggressive attack without sounding mean is just tough for anybody. And he's just not a great speaker, and he can't get the setting on short notice.