Some people aren't happy with the changes but it's really just going to the macro view. There are still very important buildings and hubs though. My only two critiques are they don't really tell you about the hubs doing more than extra storage. (There's a heat one and the storage ones can reduce workforce requirements) So just like in the first game there's a benefit to building in patterns. Some districts can even go to zero heat required under normal conditions. My other problem is the end game isn't properly explained. But if you check your damaged districts you will find new options for dealing with them in the last chapter.
Other than that it's a new format, a new story, and the same long lead crisis simulation. By the time you realize you're screwed, the mistake was hours ago. Expect to fail until you see where the resources interact with each other and figure out a sustainable research/build order. It's not just a city builder, it's a survival city builder. But there is a utopia mode if you just want to make pretty cities.
This is a major change in formula. You could absolutely play the first one without feeling like it's the same game. The story in the second doesn't require you to play the first one though.
I think it’s worth playing the first because it’s a much smaller scale and sets up the world. This one is set 30 years later so the society from the first game has significantly grown and expanded, with a lot of the evolutions in gameplay stemming from that. You probably could jump right into the second, but you may feel like you’re missing something at the start.