In the latest Guild Wars developer update the team outlines some major changes made to the Dervish class. These changes have gone live with the latest update. The devs said:

"We've taken a close look at this profession and determined that it has a lot of unique and interesting mechanics, ranging from avatar skills to enchantments that have end effects. However, these fun and original mechanics are hampered by cast times and long disables, making it hard to utilize this profession to its full potential. To address these problems and make the Dervish a truly great class, we've made major changes to nearly every skill he uses. This may seem overwhelming and confusing at first, but we feel that these changes will make the Dervish a much more enjoyable character to play, while emphasizing the types of skill interactions that defined him to begin with."

For a full list of the changes check out the official post of the Guild Wars site.