The Goddard Earth Observing System Data Assimilation System version 5 (GEOS-5 DAS) has recently been developed at NASA's Global Modeling and Assimilation Office (GMAO). The system uses a new atmospheric global circulation model (GEOS-5 AGCM) combined with NCEP's new Gridpoint Statistical Interpolation (GSI) analysis package. The system is being employed in high resolution (0.5°x0.666°) global analyses for weather and climate applications. Global forecasts at 0.25°x0.333° using the GEOS-5 AGCM initialized with GEOS-5 analyzed meteorological fields have also been conducted during summer periods to contribute to tropical storm predictions. We will assess the performance of the GEOS-5 system using a variety of high resolution satellite data sets. For example, vertical structure of DAS and forecast cloud fields are compared with CloudSat observations. High resolution/high frequency estimates of precipitation from TRMM are used to examine the evolution of mesoscale systems such as tropical cyclones. We also examine analysis tendencies/corrections in DAS experiments using different AGCM physics tunings. These comparisons provide useful information to help guide further model development and system tuning.