I have been playing Avatar now for over 6 years, and first got involved when my then 9 year old son started playing. I was impressed by the care taken by staff to ensure all players feel comfortable there, and that younger, older, non-English speaking, and other people are respected.
The game-play itself is addictive and fun, and the playerbase is large and constant. As an Australian, I play in the "off hours" for the US, but there are always plenty of people on-line.
Avatar has progressed and evolved over the years, but remains consistent, fun and addictive.