This is an issue many Japanese learners come up against, particularly if they live outside Japan. After all, If you are not in country, it seems difficult to justify huge amount of time that learning Japanese characters seems to require.
So what are problems in using Romaji (Roman letters, like characters you are reading right now) for studying Japanese:
1. Mother-Tongue Conflict
The associations your brain will create between Japanese words written in Romaji and English words (or those of your mother tongue) greatly increases risk of mispronunciation. Japanese symbols will have none of these associations for you. The very fact that they are completely alien helps you to start your language learning experience from a blank sheet. Your chances of being able to gain correct pronunciation soar.
2. Show Me The Romaji
Your textbook may be in Romaji, but you will be very hard-pressed to find any real examples in Japan. Of course, you can see a fair amount of reasonably understandable English, but not Romaji. And watch what happens when write some Japanese in Romaji and show it to your native speaker friend: They have a really hard time deciphering it, because Japanese people just donít it.
3. Todayís Crutch Becomes Tomorrowís Burden
If you decide to continue your studies in Japanese, you will eventually need to start to grapple with characters themselves anyway. In my opinion, it is harder to leave crutch of Romaji behind than it is to bite character bullet at beginning of your studies.
As you can see, there are serious problems with using Romaji when you start to learn Japanese. So what is my advice to learners? Well, it really depends on your motivation and needs:
1. The Serious Student