Materia Magica is well organized, colourful and full of helpful players.
The website is beautifully designed, with players submitting their own creative works to share will all.
The game keeps changing and evolving, and player input is effective, if done politely.
Materia Magica is completely free, with no ads running on the website whatsoever. The players support the game, but it is not necessary to donate money to be a good player or to have fun.
I believe that Materia Magica is the best text-based online world out there, easy to read and fun!