See the poster up there?
None of the action shown actually happens ingame, besides the guy shooting out of the window. Also, that lady on the far left with the glasses whom everyone thought was going to be the bad person was actually just a minor character who you briefly talk to.
It's a bit of a letdown.
Another aspect that plagues the game is that it never actually succeeds in being dramatic, even in its second half. The most dramatic aspect would be the last two minutes, much like in Shadow of the Templars. Ironically, the ending feels like a mix of Shadow of the Templars and Smoking Mirror. Sleeping Dragon probably had the best ending sequence, living up to its actual name. As stated in the poster example above, characters can seemingly perform unnatural feats in The Serpent's Curse which prevents them from actually being in any real danger, also avoiding any of the 'action' shown in the poster. If you play the game and get to this point, you'll know what I mean. There's never any real feeling of danger in the game.
But what was the actual 'Serpent's Curse'? It wasn't really a curse, as far as I can tell. Not amongst all the history dumping that was performed (admittedly, I skipped most of the dialogue in the first bit of the second half as it was basically an infodump and recap of the painting that we found in the first half). The story and gameplay feel really detached. Had there been action sequences like in Sleeping Dragon, and actual panic like in Smoking Mirror (which had action even from the very first minute, though admittedly lagged until the docks sequence), the game may have fared a bit better. Obviously, I think Smoking Mirror was the best game in the five, with Shadow of the Templars coming next, then Sleeping Dragon, Serpent's Curse and finally, the Angel of Death.
It's an alright game, but filled with far too many nonsensical puzzles in the second half, silly innuendos (the LED statue ;-;), and an unsatisfying plot. It falls a bit too flat for me to recommend, but if you want to give it a try, go ahead. It's better than Angel of Death, at least!