You play as the American Marine, Sam, looking for a way home in the city of Vladivostok. The story never strays far from that theme and never gets more exciting than that.
On the other hand, the gameplay is superb. If you want more of Metro Exodus' mix of shooting and steath, this is probably better than any comparable sized part of the main game. There is a lot of varied action. Mixed in there are also a couple of first-person in-engine cutscenes, including a fantastic one of Sam in CQB with several mercenaries. And the in-game city actually looks like the real city.
I almost give this five stars. Two things hold it back. One: boring boss fights with the same boss, not once, not twice, but three times. Two: Sam feels too much like an outsider. I couldn't find any emotional truth when playing the DLC. Coming from the main game where despite being a peaceful person, I meticulously killed every last cannibal I could get my hands on for hurting Anna, the lack of emotional investment was disconcerting. I just couldn't care if Sam got home or not.