After watching the gameplay videos for Theif 1 and 2. I don't think it is the best stealth game i have seen better game mechanics and visuals. Theif feels basic.
Dishonored has taken the crown and is highly rated for all the right reasons, how many games could you replay and then replay again...
Try some Thief videos instead.
You have to try it to know. Watching vidos doesn't work. You have an array of true to life features in Thief, such as leaning forward to look down a railing or out of a window, walk slow, creep super slowly, run ducked, lean into doors to evesdrop and more. It's a stealth simulation.