I like what I've read, but with a couple of cavaets. Ruby is the way it is on purpose. Discouraging people from using features of the language because the OP (presumably) does not understand how to use them: that's an anti-pattern.

The and and or keywords are banned. It's just not worth it. Always use && and || instead.

If you find "and" and "or" not to be "worth it", it tells me that you don't understand the difference. The "&&" and "||" versions bind more tightly, and that is not always desirable. Perl has the same set of constructs, and the Perl monks have been using them correctly for years.

As you can see all the classes in a class hierarchy actually share one class variable.

Well, yeah. That's meant to be a feature of the language, not "nasty behavior". It's good advice to use class instance variables, sure. But let's not imply that Ruby is a badly designed language; it's quite well-designed. This isn't Javascript. :-)

edit: formatting