The best expansion pack to The Sims.
First, there is a new location added to Sim City, the downtown, packed with shops and other venues where you can invite other Sims, especially the ones you have a romantic interest in. The best thing about downtown is that the time spent there is independent of the time spent in your home. This allows you to pack so much more activities and socialising into the day. No more hurried chats with the neighbours between a busy job and trips to the bathroom and eating.
Second, Hot Date vastly expands social interaction possibilities. You have a better control of what your Sims are doing while meeting with others, more interaction options, there are now two "friendship" scores reflecting the short-term and long-term quality of a relationship, the Sims now have interests, changeable through reading various magazines bought in the downtown which influence how well two Sims get together, there's a possibility of marrying two Sims and more. The expanded socialising really makes The Sims a much richer and more enjoyable game.
Bottom line: a must-have for anyone who liked The Sims.