It's a part of my favourite ever game series , Thief for me will never be surpassed, Deadly Shadows is part 3 and it's great, even allowing for the technical issues of playing it on modern machines.
Like many others I was faced with gameplay problems after launching -
Lockpicking not working at all
Garrett not able to climb ladders
Using climbing gloves on walls resulting in falls and damage taken
Some save game issues
Garrett floating above ground and unable to jump.
Most of these are solvable without having to download mods, and that's a relief because I was unable to download the sneaky upgrade. TBH the game looks fine as it is for it's age. For lockpicking and ladders, simply a matter of pressing a button (Prt Scr) for a couple of seconds after right mouse to interact with the door or chest, This also works on ladders, I had to hunt around for this solution as I could find nothing helpful in Steam forums and discussions,
For floating Garret, firing an expendable arrow should sort it.
Corrupted save files and occasional crashes are harder to deal with. I played through the whole game using just one save slot and it worked for me.
Anyway, it's all worthwhile because the game is superb as were its 2 predecessors. They are sometimes intense, and sometimes provide some moments of hilarity, 9/10 game.

The third Thief game is a decent title for what it is, but I find the game a little lacklustre in what it brought with it. While the main levels are really good, and the improved graphics from the last game are nice, it lacked elements that could make it good sequel - the briefing sections the first two games had, in particular - while the hub areas, while a nice distraction, are a bit bland once the special side jobs are gone, not to mention the shop system is a bit poor.

A decent game, which is a little better if you find the right mods to improve upon it.

doesn't work:(