(1) Syntax wise Ruby is a lot easier and more expressive than Scala. IMHO I feel that Ruby is an OO language with some functional sprinkles while Scala is a functional language with OO sprinkles.
(2) Ruby has a great ecosystem if you are building web apps. It's also got a lot of testing libraries. :) But in seriousness the number of libraries in non web/tooling space is slowly increasing as faster Ruby implementations have become a focus point. Also JRuby allows you use the vast ecosystem of Java from within JRuby.
(3) Performance wise I'm pretty sure Scala will outperform Ruby. I don't think JRuby will be able to compete either. Charles Nutter, JRuby Core developer wrote this blog post which explains why Ruby is hard to optimize ― http://blog.headius.com/2012/10/so-you-want-to-optimize-ruby...
Of course take everything I've said with a bag of salt! :)
(2) Ruby has a great ecosystem if you are building web apps. It's also got a lot of testing libraries. :) But in seriousness the number of libraries in non web/tooling space is slowly increasing as faster Ruby implementations have become a focus point. Also JRuby allows you use the vast ecosystem of Java from within JRuby.
(3) Performance wise I'm pretty sure Scala will outperform Ruby. I don't think JRuby will be able to compete either. Charles Nutter, JRuby Core developer wrote this blog post which explains why Ruby is hard to optimize ― http://blog.headius.com/2012/10/so-you-want-to-optimize-ruby...
Of course take everything I've said with a bag of salt! :)