Google also launched an iGoogle gadget that provides similar functionality. The gadget is only a wrapper for the standalone version available at http://mail.google.com/tasks/ig, a page you can bookmark or add it to your sidebar in browsers that support this feature (Firefox, Opera).
Gmail Blog explains that the most important competitor for Google Tasks is paper (I remember a similar statement regarding Google Calendar). "Among the world's leading productivity tools is an advanced technology known as paper. Many of the world's top corporations and most active internet users have adopted paper as a method of organizing their daily lives. (...) When we set out to build Tasks (now in Gmail Labs), one of our goals was to improve upon paper. With the version of Tasks in Gmail, we focused on making editing very fast and simple -- as close to paper as we could."
Hopefully the next iterations will bring a proper standalone version, the integration with Google Calendar and an API that will facilitate synchronization with other applications. That will give Google Tasks competitive edge over paper.