There are at least three advantages for learning the radicals.

1. It will help you to remember characters. In some cases, radicals can also give categorical information. For instance, the character忘to forget is formed by the radical 心 heart and 亡 perish. The heart radical often associate with words which imply thinking such as 想 to think.  The character想 to think is formed by 心, the heart radical and the character 相, it is pronounced xiāng which is similar to the character想 xiăng.
2. Radicals and components are used to describe characters. As there are many homophones in Chinese, characters are often are described by their radicals and components. For instance, if you want to describe the character河river which is pronounced hé. As there are many characters sharing the same pronunciation, when a Chinese person describes this character to you he or she might say: “water radical氵with the character 可.”
3. Most importantly, Chinese characters are often catalogued under a radical index in a dictionary. Without knowing radicals will be impossible to use a dictionary. However, the radical indexes in Chinese dictionaries are not always the same. For example, one character can be listed under a particular radical in one dictionary but can be listed under another radical in a different dictionary.