My personal reaction was that Trump's speech was horrifying, a dystopian vision that bears no relationship to what is actually going on in this country (e.g. violent crime continues to fall, trade continues to make us wealthier, immigrants continue to make productive contributions, etc). Peter Suderman has more in case you missed it.
But in Arnold Kling's 3-axis model of politics, the speech made perfect sense. Trump has decided he is going to run hard on the civilization-barbarism axis. The barbarians are at the gates, and his opponents are either too weak to deal with them or are actually in league with the barbarians. He is the strong leader who will turn them back and make everyone safe again. We're not going to trade with the barbarians, we are not going to treat with them, and we are not going to waste civil rights on them. Ugh. Trump is working hard to make me feel the victim, but I don't accept victim status.
I am not sure if this is marginally better or worse than what we are going to get at the Democratic Convention, where we will get four days of hearing that I personally am the bad guy and source of all misery in the world and the person that needs to be regulated harder and looted more furiously. I almost prefer the Democratic approach, because at least evil is being done against me rather than in my name.