Well The_Super_Inframan told me to have fun with Mata Hari, so here are some impressions:
The length: I've put 3 hours into it and I surmise I'm about halfway done, considering I've done the chapters 1905, 1908 and 1912 and we all know what happens to her in 1917. So it's a decent length.
The graphics: The backdrops are beautiful. The characters vary: some look good, some look like early ventriloquist dummies - something about the way they make the eyes move. Mata Hari herself is shown to look more flattering than the actual photos we have of her. And they don't skimp on the fanservice: you get to see her in skimpy dance attire and so far I've seen her in lingerie twice now. So it's got that going for it, which is nice(?)
The storyline: History tells us that Mata Hari was a Dutch woman who took on a persona from "the mystic east" and did exotic dancing in the 1900s and early 1910s, and who was executed for spying. (History is actually unclear whether she actually was.) That said, the game gives us a fanciful what-if story that takes us to Paris, Berlin and Monte Carlo as she plays double agent, but so far it seems she's mostly spying on the Germans. It's alright for what it is.
The dialogue: It's well-written. Mata herself has a few coy turns of phrase as she flirts with characters, but in keeping with the times it's never explicit or slutty. Some accents are better than others, and by that I mean some voice actors try to put on a good accent, and some don't bother at all. So you'll get a half-decent German accent from one German character, and another with no accent whatsoever. That can be jarring, but on the whole, the voice acting itself isn't bad.
The gameplay: Some puzzles are interesting in their dialogue base: using one of four different approaches to win a man over, getting them to reveal secrets while they're sleepy, and so on. The minigames, however, get a bit rougher. You know those puzzles where you switch and rotate pipes or wires? Yeah, it's got one, and it awards points based on how FAST you do it. These points apparently go towards how good an ending you get. There's also a dancing minigame. Rather than hit buttons in time with music, you MOUSEOVER circles as notes enter them. Got two notes in the same place? Don't you dare keep the mouse inside that circle, or one of them will be 0/10 points (because you mouseovered the circle too early, you see?) The first dancing minigame was okay, I passed, just barely, but said to myself "Okay, you got this, next time you'll do better." Second one was significantly harder. I can only imagine what it looks like in the end. There's also a travel minigame where you have to avoid foreign agents. You'll do this one a LOT. They give you an option to take express trains to skip the minigames, but again, doing so will apparently affect your ending. To top it off, they have "secret missions" which essentially means, "did you find these missable objects?" That can be good or bad, depending on your point of view. In my current mood of playing point-and-clicks, it's bad.
The verdict: It's a good-looking game and not without its charm. However, if you like point-and-clicks to not judge you based on how well you do minigames, give this one a pass. Otherwise, it might be worth your time.