I'm opposed to using it for beginners who aren't familiar with the phonetic system of the language. Once you learned the phonetic system properly, and you know the character's in Romaji and Pinyin don't represent the sound you know in English, of course it's then helpful for learning how to type Japanese or Chinese.

Don't get me wrong, Romaji has useful purposes, such as representing place names in Japan for foreigners, etc. But as a learning device for learning Japanese, it's not a very good one.