Bruce Tate's article on alternatives to Java mentions many of the aspects of ruby that I'm growing to love.
It wouldn't make sense to repeat them all here, others have stated ruby's strengths far better than I.
However, I would recommend giving ruby a shot. I gave this language a cursory look a couple years ago, after seeing a /. posting. At the time I thought "Hmmm... it just looks like a slightly better scripting language".
In some ways I feel I was right, ruby offers evolutionary improvements over other languages. But in many ways I was wrong, because the sum of all its improvements make ruby stand out compared to its peers.
What I like the most about ruby is its intuitiveness. Whenever I learn a new programming language, I always feel that I'm stumbling around at first, stringing together keywords thinking "I bet this won't work" because I haven't internalized the language's ideosyncrasies yet.
Well, in ruby I'm finding to my surprise that my bets are wrong, things do work the way I think they should. A language that intuitively makes sense is worth cherishing.
Here are some resources to get people started:
- One click installer for Windows and OS X
- Matt's (creator of ruby) introduction to ruby (fast, worthwhile read)
- 10 Things a Java Programmer Should Know About Ruby (another good intro slide deck)
- Programming Ruby (the canonical reference, also included electronically in the one click installer)
- Last but not least, Ruby on Rails (because this is where the fun is!)