The first Kingsman movie was so well received that it resulted in a sequel. The sequel was not as well received. Kingsman: The Golden Circle didn't do badly. It was still financially successful, although it didn't do as well as the first film. However, the sequel was critically lambasted compared to the first movie. Taron Egerton now says that the negative response hit him hard, mostly because he put his all into the film. According to Egerton...
Nobody likes to have their work criticized, but when you're an actor that's going to be part of the game. Both professional critics and fans are going to tell you what they think and when they like the end result it's going to feel good, and when they don't it's not.
Taron Egerton tells the Empire Film Podcast that the negative response to Kingsman: The Golden Circle hit him especially hard because he specifically worked hard to make sure that he did everything he could to make the movie work, and the response apparently made him feel like he was unsuccessful in that regard.
Often bad reviews are no big deal to actors. Sometimes it's because the actor was never particularly invested in a project, but clearly, that was not the case here.
While Egerton admits that The Golden Circle had some issues, that it maybe wasn't "put together" as well (which potentially covers a lot of ground) that he still overall feels it's not a bad film. While a lot of critics would disagree with that sentiment, I wouldn't. While I certainly think the sequel isn't up to the standards set by Kingsman: The Secret Service, it's still a perfectly fun little movie. If you enjoyed the original there is certainly fun to be had with it.
It will be interesting to see how the response to Kingsman: The Golden Circle impacts the franchise. Several different films are currently being plotted, some with spinoff characters and some set in different time periods, as well as a proper sequel starring Taron Egerton. Certainly, these other sequels will be looking for a warmer reception than the one the last movie got, which could mean some reevaluation before they make it to the screen to make sure the films are up to snuff.