Most of the criticisms that reviewers are making are valid for the most part ...
Bigger isn't always better and it seems unanimous that reviewers agree that XCX has a weaker level design compared to the predecessor. The game brings in less favoured aspects too from the predecessor like how it is cumbersome to learn the mechanics and the less than ideal side content too. The reviewers feel that the story is weaker and it doesn't help that we have a protagonist that doesn't speak up. As for the the soundtrack, it too appears to be weaker than the predecessor and as for me I really don't like most of Hiroyuki Sawano's compositions either (In fact I hate them.) ...