I'm not sure how I feel about this. For a start I think this will be better for the employees, Activision Blizzard has had a terrible time with their workplace culture so hopefully Microsoft will sort things out, although Microsoft is a huge corporation with corporate interests, so I wonder how much will be improved.
As for the games, my hope is that they focus on the smaller IPs like Crash and Spyro. We may see COD instalments every couple of years or so instead of annually, so if you're a COD fan (who owns an Xbox) then this should be better for you. As for COD and other Activision franchises being exclusive, well Phil Spencer was very careful with his words - almost as if it was "lawyered up" (I'm a lawyer, so I recognise lawyer speak when I see it). His words were ambigious because he said Microsoft would honour all existing contractual agreements, but we don't know what they are. Could it mean that for the time being, games like COD will be on the Playstation? will Microsoft make the games exclusive to Xbox? they just spent $70 billion so there's a good chance these games will end up being exclusive, but I imagine Microsoft will want to keep the big titles like COD multi-platform until they are able to sell more Xboxes.