Fantastic mission design makes this one worthwhile despite dated gameplay mechanics.
Cons: High reliance on trial-and-error; Disconnect between cutscenes and missions in terms of story; Graphics are, in an essence, last-generation; Several odd design quirks
The hunter has become the hunted. This is what Hitman: Blood Money's story essentially boils down to. World-class clone hitman Agent 47 has been targeted. In between missions, well-directed cutscenes follow a reporter as he is told about Agent 47's capture and demise. All missions in the game are related in past tense, getting closer and closer to the alluded conflict. It's an fascinating set-up that constantly teases you onward while providing interesting political ideas on the topic of cloning.
The only issue here is that there is a pretty large disconnect between the missions and the story. With the exception of the last two missions, the two remain largely independent. The overall feeling is one of a mission pack with story during the intermission. It cripples the potential of the story as you don't feel truly involved for the most part.
However, if it can be said that Hitman: Blood Money is a mission-pack, it is an extremely good one. The mission process generally goes as follows: get a mission briefing that tasks you with killing a few people and perhaps collecting something; choose your weapons and start the mission; choose your path towards the goals; escape. However, the broad set-up gives you a lot of methods to complete your goals, making Blood Money an extremely open-ended stealth experience.
If you want to steal a uniform and stalk the target until you can isolate and kill them, go right ahead. If you want to sneak out of the way and create an "accident" scenario, you are free to do so. If you want to go in guns blazing and tear up the whole place, be my guest (though I wouldn't recommend it, as Blood Money isn't intended to be a true shooter and is lacking in that respect. The varied and colorful missions are all expertly designed to allow for a variety of methods. Although you'll usually have to try more than a few times to get a working method (and even more to do so unnoticed), planning and executing the perfect silent kill is extremely rewarding.
Behind the great mission design and replayability, however, are dated mechanics and graphics. Many functions, such as taking a disguise and hiding a body are more complex than they need to be, and AI is often unrealistic and behaves erratically, and the game can have surprising limitations at points. Furthermore, the graphics are essentially a high-res, lighting enhanced last-gen game. Animations are fairly stiff and simple, most objects are basic and smooth, and many animations are outright skipped (example: 47 changes clothes by simply bending down and warping into the new attire. Not that we really want to see him stripping down before changing).
Hitman: Blood Money isn't going to revolutionize the world. Released as a quick port from a game for the last generation, it feels somewhat dated in the modern gaming world. This doesn't stop the experience from being a fun one though, thanks to some great scenarios and mission design. If you aren't averse to old game design flaws, you may want to check this one out.