Underrated
The game is save point system and I'd recommend you to put some points in sabotage skills to beat mini-games if you'd like to go for stealth. The mini games are not well designed like ones in Deus Ex:Human Revolution, where the players are allowed to use some resources to cover the protagonist's skill. In AP, It is mostly about characters skill not yours - the end of the line. The same goes with aiming, you need to stay still if your character is not good at shooting, which must be counter-intuitive to shooter players.
While character skills are important, unfortunately again, you will be hit by the brick of "This is an old-fashioned RPG." You need to spend point on a skill but it is mostly presented as numbers rather than descriptions of what the skill actually does. Despite of my nostalgia, if you build an action game, you shouldn't bother your players with *unnecessary* complexity.
Now, about the choices in the story, and characterization of the protagonist, that's where this game shines. You can pick missions in the order you want and your choice is reflected on the outcomes. Depending on the order, you may be able to influence more on a certain people while you may miss even a character when you pick the place later in the game. Gaining good reputation for a character may attract unnecessary attention from him and you may be plagued by him. Some decisions make some characters happy while the same decisions can make other characters angry. If you have quite many friends all around the world, you can have quite good information about the whole picture but probably some of them are still unavailable to you in just one play. After all, it's a spy game.
The characterization of the protagonist is also an interesting part. You cannot only play as an ass, or a nice guy but you can also be quite outlaw-ish or dutiful. You can be a Don Juan while an absolute gentleman who doesn't sleep with any girl in any situation. Furthermore, an ass or not, you can still play a trick on some characters and outsmart them, depending on how you play the game.
After all, if you haven't played it and can feel quite generous to the old style RPG concept and like choices in dialogues, then, why not give a try to this hidden gem? Well, it definitely has its rough edges but, at the current price, you cannot lose too much.