I have been looking into many open source platforms to help a client to develop an exciting website. It has requirements for community networking, forum, digg type topic discussions with voting/ranking, profile/member ranking/voting and more.

I have not used Drupal yet, but wondering which template platform I should use to build my client's site.

Can anyone give me some input on how easy it is to customize or add extensions/plugins etc to Drupal compared to others and if it is the best solution for my client's site?