I think the main problem really is that it's called a sequel. If instead it was described and promoted as a spin-off or its own thing, then it could be judged simply by its own merits. And on its own, this is not a bad game. Maybe not for everyone, but every prongame is subject to individual preferences. And for what it does, i would call IV2 a 3,5 out of 5 in its current state (could be 4/5 with more content).
But since its presented as a sequel, all kinds of criticism relative to the first game apply. For starters the core gameplay loop is totally different, with the addition of a static base and all the ressource management. So this 'sequel' kinda isn't even the same genre as the first. And that's just one valid point of criticism out of maybe a dozen.
So it's not that IV2 is a bad game in its own right. It's "decent" right now and could become "good" with more content. But in no way is it a "sequel", and calling it that is bullshit. It's a "spin-off": A totally different game in the same thematic universe.