Underwhelming as usual in my opinion. I mean, they've clearly tried to push some new ideas and concepts and the visuals (at least in the environment showcased in the video) seem a bit more polished. But at the end of the day its still virtually the same arcade shooter it has been for I don't know how long now.
Its getting more and more difficult to tell the difference between new COD titles. I personally don't like this, but that's probably just because I'm not a huge COD player. Fans of the series will probably appreciate this as it allows them to jump right into the next title and get their next kick of new mechanics and weapons without having to go through the process of learning something new. Its hard to put into words but what I'm trying to say here is that the developers aren't pushing something entirely new because that's not what the fanbase wants.
COD is virtually a cash cow at this point (as opposed to a passion project) and Black Ops 4 clearly reflects this. They make what brings in the millions. And there's absolutely nothing wrong with that. There are dozens of other new titles to try out anyway.