Open Radio Access Network (O-RAN) has emerged as a disruptive paradigm for mobile networks, aiming to disaggregate traditional RAN functions into software-based components connected via open, interoperable interfaces. By enabling multi-vendor integration, programmability through rApps and xApps, and cloud-native deployments, O-RAN promises to foster innovation, cost efficiency, and operational flexibility. However, validating its feasibility and performance requires realistic experimentation and the use of testbeds. This paper provides a review and practical evaluation of O-RAN testbeds, ranging from experimental deployments to fully simulated frameworks. We first introduce the architectural principles of O-RAN, highlighting its key components, functional splits, and open interfaces. Next, we survey relevant research testbeds and prototypes reported in the literature, analyzing their architectures, design choices, and lessons learned. Finally, we reproduce and assess four representative implementations, including the NIST automation framework and ns-3?based O-RAN simulators. A comparative analysis is presented, discussing advantages, limitations, and alignment with evolving O-RAN standards. Our findings indicate that while automation frameworks simplify reproducibility and simulation frameworks enable flexible experimentation, interoperability issues and the lack of maturity in the Non-Real-Time RAN Intelligent Controller (Non-RT RIC) remain open challenges. These insights can guide researchers and operators in designing future O-RAN testbeds and accelerating the adoption of open and smart RAN solutions.