ALICE has undergone a major upgrade in preparation of LHC Run 3 (2022-2025). The new Inner Tracking System is completely based on Monolithic Active Pixel Sensors, the Time Projection Chamber was equipped with GEM-based readout chambers, and the muon system was upgraded and extended by the Muon Forward Tracker. New trigger detectors were also installed to allow the clean identification of interactions. In addition, the readout of all detectors was upgraded to make use of the increased luminosity expected from the LHC. Furthermore, the computing infrastructure and software stack have been redesigned for continuous read-out including a synchronous reconstruction stage making use of 2000 GPUs to achieve the required computing performance. In this presentation, we will report on the installation of the upgraded detectors and computing farm and the first experience from operation with with pp collision.