It's pretty much exactly the announcement I expected, and I think the announcement anyone would have expected if they were reading between the lines rather than... well... dreaming. This is very precisely Microsoft's answer to the PS4 Pro, and though it should comfortably be the best console (for at least a couple of years), and while I think there will be noticeable differences across many titles, I don't see it making some dramatic difference to the shape of the console market. The two mid-gen refreshes should see the power gap more or less reverse, with Sony being a bit in the lead in the first half of the generation and Microsoft being in the lead in the second half.
The two remaining questions regard price and games. I don't think it's impossible to imagine this being a $400, but there are various things that lead me to believe it's going to be $450 or even $500, just given the way that Phil Spencer has talked about the 'premium' nature of the product. In some ways, at either price point, I think the product will be reasonably successful because it's going to be the best hardware on the market for at least a couple of years.
The games question is a lot trickier for Microsoft to answer, I think. I wonder whether they have a stable of developers which is going to be able to maximise the power of Scorpio in the way that Naughty Dog, Sony Santa Monica, Sucker Punch, and Guerilla will maximise the power of the PS4 Pro.
On a personal level, I'll definitely be considering purchasing one to replace my Xbox One come November, though if it's above £350 in the UK, I'll probably decide against it, at least in the beginning. It really depends on whether I'm spending much time on my Xbox One around that time, because right now I'm using it once a week at maximum.