It's something that has been said a million times before, it's simply a way of saying "you are a hypocrite and your criticism isn't valid, this is actually a great country, one of the best".
I agree I've heard this phrase many times in my life of 66 years. But his is the first time for a US President or high government official to say this in public. So that makes it more unique and interesting as to how the public responds to this it should be very educational for every one.
I think this thing is going to be one for the history books, it is definitely causing me to think a lot more about the issues of racism, gender, proper ways to address members of Congress by the President. Should be a very interesting next few years.