I'd say both games had their problems. If you have an older computer, and are willing to try and figure out the navigation, China may be worth a try. If you don't, I don't know how much you can slow the game down on a modern computer.
And when you said you "got dispatched," in The Messenger, did this mean you got killed?
Yup. Happened a lot. You go outside, or somewhere where a guard sees you, and it's back to the save/load menu. And because of the nature of the interface, it can be hard to tell where a click will take you or where there will be a guard lurking. There were plenty of places I thought were dangerous that weren't and objects or hotspots I clicked on that didn't look dangerous but were. That meant I had to be saving the game all the time, and reloading from a save often. I got fed up with it. The game advertised being able to explore the Louvre in 5 different time periods, but that turned out to be a gross exaggeration. I could only explore parts of the Louvre, sometimes only very small parts, per time period.