I'm actually in Japan at the moment studying the language. I was enrolled for 3 years of college level Japanese. We used genki throughout all 3 years of the class. I'd have to say that nothing bolsters your skill like being here and having to use it. I came here with poor speaking and listening abilities, but now, I feel I can hold my own in a Japanese conversation. I'm not arrogant enough to claim I'm fluent, but I think that I can stumble through a sentence and have the person on the listening end understand what I mean. If you're looking for something beyond genki, or something supplementry to genki though, I'd recommend this book:
http://www.amazon.co.jp/gp/switch-la...nguage=en%5FJP
It has some repeat grammar from genki, but I really like the way the book is broken up. It takes the different conjugation patterns and gives you verb endings based on that. It's what we're actually using in our classes here. It's meant to prepare you for the JLPT.
And on the topic of why I decided to learn this language, at first it was a mild interest because I liked video games and anime. Now, it's a career driven skill for me. Being bilingual is a valuable asset and damn good resume material. But if you seriously want to study the language, I'd say get some grammar under your belt, and try and come here. I've learned more here in a few months than I have in the 3 years I took the class.
Jam it back in, in the dark.