i belief, i should share this story, once i heard about apatana (eclipse based) ruby IDE i gave it a try without being late, later i heard Net beans got ruby supported, again i wasn’t late and gave it a try.
as you know, i am java developer, always like java stuff everywhere (if possible). anyway, later i returned to my favorite IDE IntelliJ idea.
my personal judgement in terms of usable and flexibility i must say, intelliJ idea with ruby plugin just rocks!!
currently i am developing a active record kind of things where i am using java based repository model in back end and my restful web service clients are developed on ruby.
i am pleased with intelliJ idea, as because the ruby plugin is too friendly, though i faced lot of internal code hints related problem, but i could see those problems were fixed on new release.
here is the ruby plugin details page