It was short. Presidential addresses typically run much longer - I guess they think that if they're going to barge into your living room they may as well make themselves at home. Trump said his piece and got off the air.
It wasn't an elegant speech in the Reagan (or even Clinton) mold. I think that this is a big part of why the establishment hates him - he does not follow their norms or aspire to their goals.
It was an effective speech. It's said that Winston Churchill's most famous speeches ("We shall fight them on the beaches ...") used simple words. Old words, dating back to Anglo-Saxon times. Words that would resonate with the population. I think that Trump's use of vocabulary is similarly chosen, and it works. Not in the Acela Corridor, but in the places that voted for him.
Boy, did Chuck Schumer and Nancy Pelosi look like they had swallowed something unpleasant. It seems that Trump's speech wasn't published beforehand and so Check and Nancy had to think on their feet. That's clearly not their strong suit and so they fell back on the usual pablum.
The address was a huge challenge to the Democrats. It will be very interesting to see which way the polls break (assuming you trust the polls, that is).