Since the question is not closed yet, and yet Chinese (both Cantonese and Mandarin) is quiet the same in this question, I would still like to answer it.
Actually the radicals is not essential, unless you would like to look up the Chinese dictionary.
You should know that the pronunciation of Chinese word mostly don't base on the radicals. There are six structure of word in Chinese, which is called 六書. The major Chinese words in use now is phono-semantic compounds and most radicals are not the phonetic component.
Many radicals are basic words that you should learn; however, you don't need to learn all the radicals since some of them are too rare and even native speakers don't know how to pronounce it.
Hope this is still helpful to you