Good stealth games are hard to come by, at least the hardcore ones, but this one does not disappoint.
The plot is really well presented, you don't know much of it at the start, but as you play it the more engaged in it you get. It starts with a faction asking you for help (not willingly) to retrieve a certain artifact from a church of the religious Hammerites. At first Garrett, the main character, not wanting to get involved in any political game refuses, but then thinks of all the good stuff he could "borrow" while he's there... What starts simple, gets a little more complicated later on. Not spoiling anything, let's just say that it is somewhat unexpected (but in a good way!) and surpsisingly scary sometimes (yes "The Cradle", I'm talking to you).
The game encourages you to really sneak around and not be detected, since a confrontation doesn't end well for the player in most cases. But don't think that this is an unforgiving game, as the game provides the player with a good variety of tools to make all the sneaking around possible. For instance, there is the Blackjack that can be used to knock enemies out silently, there's the Water Arrow which is used to extinguish fire based light sources from a distance creating areas of darkness, the Moss Arrow that is used to create a grassy spot where it isn't noisy to walk on, or the option to simply grab something fom the environment and throw them to lure enemies away. And if you screw things up, there are also the "escape" tools as well, like the Flashbang, that blinds the enemy giving you time to hide again, the Oil Flasks in which the enemies can be slowed down in case of pursuit by sliping on them (or to be set on fire if shot with a Fire Arrow, creating a true firewall), and so on. And if you really need to fight, you have your bow (which can kill the enemy instantly, but only if he/she is not aware of your presence) and dagger (you can also backstab unaware enemies with it), which is possible to guess, isn't very effective in a direct assault on armored sword wielding angry guards (but possible to beat with the help of some Health Potions)
With all of the tools in the game, it is even possible to beat the game without a single confrontation, lethal or non-lethal. These items give you a nice balance in the game, making every mission possible to be approached a different number of ways.
The game can be played in a first person perspective, which is more immersive but a little more problematic, or in a thid person perspective, that makes the game easier since you can take a peek at corners without moving for instance.
As I stated before, the first person perspective can be a little frustrating, a good example of this is when you lean: the purpose of this is to be able to look from the safety of the shadows without compromising yourself too much, in previous installments of the series, this manouver was one of the most important of those games, it was easy and quick to use, in this game however instead of the character just leaning his head out of cover like it was implied by the movement of the camera in the other games (there was no third person perspective in those), here the character literally places himself to the side really slowly, which compromises you instead of giving you an edge on the enemies.
In fact, it can be dangerous to use sometimes, as it can make you fall from a ledge if you're trying to lean near one for instance. So this kinda forces you to use the third person perspective a lot more than you could wish for.
But this isn't something that can take you away from the game, it's a minor inconvenience that doesn't break the game. You can face a wall and then put your back on it if you think an enemy is going to walk by TOO close to you (can be a life saver) and the movement modes give you more strategy options: you can run, walk crouch, and sneak, each one presents a different speed and noise, so choosing carefully how to approach a place or enemy is always a good plan.
The AI can be unforgiving, or just plain stupid. Sometimes it will chase you relentlessly for a long time, and sometimes it will give up at the first corner. At least it is good to be surprised sometimes and have to adapt to a certain situation. It is just weird (but necessary in a certain way in this genre) that the enemies see you and may even engage in combat, but later forget that you were there when you hide ("It was probably just my imagination").
The game takes place in The City (that's the name presented by the game), and it is kind of a free opened world. "Kind of" because of the engine limits, since the game can't handle large areas, there are a lot of transition places which requires the game to stop and load content, breaking the pace of the game, and making it really annoying when you are just trying to explore. The missions take place in separate places of the city, and can only be accessed once, so you can't visit the mission areas prior to reaching them in the story.
Graphically, the game looks really good for its time, great particle effects lighting effects and shadow projections (which you can use to see the enemy coming or the opposite). There are a few problems with colision detection and you can get stuck sometimes requiring you to reload the game in a previous save slot, but thankfully, that's really rare (unless you want to climb everywhere).
The sound in this game is great, the musics, the ambient and the voice acting are terrific (and comical sometimes as intended). People talk about you in the streets, or think out loud that they must be seeing ghosts and so on, and that's all very convincing.
The game is pretty long, without taking consideration the times you will reload and try again going through a certain spot or the load times themselves, so it provides a good ammount of time of entertainment.
In the end, even lacking a few things that made its antecessors great (like the Rope Arrow), Thief Deadly Shadows still greatly succeeds in delivering a solid stealth gameplay and at the same time gives the player liberty to approach the tasks at hand many ways differently (but that doesn't mean without a little punishment) giving the game a good replay value. And with its lenghty campaign, it will certainly have you immersed in its world of intrigues and surprises for a good (really good by the way) time.