MUSTANG-2 is a 90 GHz feedhorn-coupled, microwave SQUID-multiplexed TES bolometer array in the final stages of development for operation on the 100-m Robert C. Byrd Green Bank Telescope. We present the camera design and report the performance during the first season of observation, in which 64 of the available 215 pixels in the focal plane were populated. We highlight the microwave multiplexing readout technology, which is envisioned as a path to read out the next generation of large pixel-count cryogenic focal planes. In this regard, MUSTANG2 is a pathfinder for this multiplexing technology. We present noise spectra which show no detector noise degradation when read out with microwave SQUID multiplexing, and we present first light images of Jupiter and M87, which demonstrate the end-to-end system performance.