As current digital libraries are becoming more complex, the facilities provided by them will increase and the difficulty of learning associated with the complexity of using these facilities will also increase. In order to produce usable and useful interactive systems, designers need to ensure that good design features are incorporated into the systems, taking into consideration end-users' needs and cultural backgrounds. We carried out a study to investigate useful design features digital libraries should have. The study provides insights on the usability impact of digital libraries for task completion and end-users' perceived impressions on the effectiveness of the digital libraries. The results also suggest that there is little provision on the interface to cater to end-users' browsing and inter-cultural needs. Hence, this paper also discusses design guidelines for the design of user-centred digital libraries.