I credit Mr. Hartl's tutorial many years ago with my decision to take Rails seriously and find a job where I got to work with it every day. I appreciated the framework, but it often seemed "too cute" or "too magical" for my C++-based tastes. His tutorial provided a sober introduction to pragmatic work with the framework that continues to influence my day job to this day.

(Apologies for never actually buying the book after working through the HTML version and loving it–I'll be sure to purchase a copy this month.)