Christopher Bird’s review published on Letterboxd :
It's a capable enough bit of fluff, but then again so was the first one and this one is, if anything, even more stupidly over-the-top, up to and including Sir Elton John doing a flying kung-fu kick. It also can't quite commit to a political viewpoint, just like the first one (where environmentalists were bad, but so were political elites, "ah fuck it let's explode Barack Obama's head") given that it wants its villain to be, well, the villain despite her having a clearly completely reasonable set of demands (granted, she is holding millions of lives hostage, but they all get to live if she gets her way, so she might be crazy but she's got an obvious point) and then further muddies that by having the pro-prohibition establishment figures be cartoonishly evil bad guys. It's just a giant kludge.
On top of that, the movie brings back Colin Firth as Galahad with a truly ridiculous plot contrivance because, well, everybody likes Colin Firth, and while I like Colin Firth too it does undo a lot of the story momentum coming in from the first movie, and then the movie kills off even more of its appeal by blandly duplicating as many tricks from the first one as possible (including not one but TWO constantly-moving-camera fight scenes set to 1970s rock hits) and adding some stupid contrivances for the sake of a joke (Marc Strong's Merlin is suddenly a John Denver fan - okay then), and having a wholly bland subplot where Eggsy really loves his girlfriend but whoops he's afraid of marrying her because of his secret agent responsibilities and uggggggggggh.
There is just enough decent balls-to-the-wall action here to make it an enjoyable watch, but it's the bare minimum. You miss even less by missing this than you do by missing the original KINGSMAN, and that one was popcorn at best.