HERA-B is a fixed-target experiment at DESY aimed at primarily measuring CP violation in the beauty system. The experiment employs an internal wire target in the 920 GeV proton storage ring (HERA) at DESY. The hadronic interactions, occurring at 40 MHz, are analyzed by a fine-grained forward spectrometer built around the proton beam pipe. The apparatus features state-of-the-art detector technologies in vertexing, charged particle tracking, hadron and lepton (muons and electrons) identification. The experiment is currently taking data with a partial detector. The performance of the detector and its physics potentials in this run and the CP run starting this Fall with a complete detector will be described.