The web has improved our life and has provided us with more opportunities to access information and do business. Nonetheless, due to the prevalence of trackers on websites, web users might be subject to profiling while accessing the web, which impairs their online privacy. Privacy browser add-ons, such as DuckDuckGo Privacy Essentials, Ghostery and Privacy Badger, extend the privacy protection that the browsers offer by default, by identifying and blocking trackers. However, the work that focuses on the usability of the privacy add-ons, as well as the users' awareness, feelings, and thoughts towards them, is rather limited. In this work, we conducted usability evaluations by utilising System Usability Scale and Think-Aloud Protocol on three popular privacy add-ons, i.e., DuckDuckGo Privacy Essentials, Ghostery and Privacy Badger. Our work also provides insights into the users' awareness of online privacy and attitudes towards the abovementioned privacy add-ons; in particular trust, concern, and control. Our results suggest that the participants feel safer and trusting of their respective add-on. It also uncovers areas for add-on improvement, such as a more visible toolbar logo that offers visual feedback, easy access to thorough help resources, and detailed information on the trackers that have been found.