Someone over at the Joel on Software forums has posted an excellent rant detailing his gripes with Ruby on Rails. I couldn't have said it better myself. The only thing I'd add is maybe a paragraph or two about the headaches involved in deploying Rails in a production environment, especially when Lighttpd isn't an option. I'm too lazy to write those paragraphs now, but suffice it to say that it can be a huge pain in the ass.