Trials of Atlantis is essentially a must-buy for hardcore fans of the game, simply because you won't want to be without the benefits of some of the master abilities and artifacts in realm-vs.-realm combat. For casual players and newcomers, if you're planning to join a guild and spend some serious time with the game, the game community is fairly welcoming. However, if you just want to dabble, you probably won't find much value in the expansion, because you won't reach the levels to enjoy it for a long, long time.