[Troo]

Well, it entirely depends on what you want to get out of learning Japanese. If you want to be able to hold down a conversation, but never read a thing, you'll not need any kanji at all. If you want to be able to read anything - whether a newspaper, a sign, some manga, adverts, food packaging, instructions for whatever you're buying, or anything featuring words which are written down - then learning kanji is probably a good idea.