Pros: Beautiful background graphics, a few fun mini-games and some great ideas...
Cons: ... but poorly executed and only of interest maybe to casual gamers.
Based on the exploits of the famous exotic dancer and spy, Mata Hari is a game that looks like an adventure game but really is a casual game, with lots of different mini-games and an extremely basic adventure game element. The interface actually seemed very flexible, which is a bit of a shame considering the game never gave you any real opportunity to use that flexibility. The game starts with a long sequence that's almost completely dialogue based and is, quite frankly, extremely tedious. (The intro is so tedious that it did in fact put one blogging friend off the game so completely that he never played the rest of it.) Get past that and the game rather improves, although it still restricts the player too much for it to every becoming really engrossing.
With it's many different mini-games, from finding things, solving puzzles, breaking codes, hidden object and adventure elements, mixing chemicals and finding hidden secrets (by sneaking round various bedrooms in basque, stockings and suspenders after making sure your latest conquest is fast asleep - okay, the basque, stockings and suspenders are appropriate given the setting, but considering the need for stealth, why is she wearing high heels?!?!?), the game is often quite fun. Each different mini-game starts with an adequate explanation of how the game works, and this can be viewed again at any time. The games vary in both complexity and difficulty; mostly pretty easy but later on one or two of the mini-games are very challenging indeed.
There is also a dancing mini-game, with your costumes getting scantier and scantier as you get further into the game. The dancing mini-game was of the "hover your mouse cursor over the right icon at the correct time" variety, and was quite fun - sometimes really easy, at other times very difficult. I have to admit that the dance moves themselves looked a bit odd - okay, very odd (and not at all exotic!), but overall the graphics were really good. The animation was perhaps not so great, but the backgrounds were often near-photo realistic. Mata has several changes of clothes and dance costumes throughout the game (though only one set of underwear it seems, poor girl), which is more attention to detail than you might expect. Strangely though this attention to detail is not carried through to some obvious things such as mirrors showing your reflection when you stand in front of them. The music was okay, certainly nice enough on the whole but a bit too repetitive. The quality of the voice acting varied greatly.
Some of the puzzles are well designed, some didn't seem so good. The main part of the game just never becomes really enjoyable though - the game so often presents you with only one real option, but presents it in such a roundabout way because of the interface, that it is more often annoying. The plot is quite good and makes you want to get further into the game (featuring characters who presumably were known to have had some contact with Mata Hari historically), but its faults and sometimes atrocious dialogue (probably bad translating to blame?) ruin any chance of it really drawing you in.
When you complete the game you get some ratings, so it's possible to go back and play again for better scores - but to be honest I doubt you'd feel much like playing it again. It's a shame because Mata Hari has some really good ideas, but the execution is lacking and marketing it as an adventure game is merely going to give people false expectations and very likely lead to disappointment. If you like casual games you will get some enjoyment out of it though (and I guess if you have a secret yearning to see a digitised Mata Hari in her underwear it may entertain you for a few minutes!). This is a game that looks great but offers very little in the way of involving game play (and even there, it was just starting to get really interesting... then it ended!). As such I only feel it's worth a 2-star rating.
For a bit of info regarding Mata Hari, http://en.wikipedia.org/wiki/Mata_Hari has some interesting (and potentially even accurate! :-D) information.