We are witnessing an increasing interest in graph data. The need for efficient and effective storage and querying of such data has led the development of graph databases. Graph databases represent a relatively new technology, and their requirements and specifications are not yet fully understood by everyone. As such, high heterogeneity can be observed in the functionalities and performances of these systems. In this work we provide a comprehensive study of the existing systems in order to understand their capabilities and limitations. Previous similar efforts have fallen short in providing a complete evaluation of graph databases, and drawing a clear picture on how they compare to each other. We introduce a micro-benchmarking framework for the assessment of the functionalities of the existing systems and provide detailed insights on their performance. We support the broader spectrum of test queries and conduct the evaluations on both synthetic and real data at scales much higher than what has been done so far. We offer a systematic evaluation framework that we have materialized into an evaluation suite. The framework is extensible, allowing the easy inclusion in the evaluation of other datasets, systems or queries