[herewulf]

The IPA is invaluable for studying human language, not just _a_ language. I.e.: For linguists.

For individuals wishing to learn a foreign language, the IPA probably isn't super helpful. Your mind needs to learn to pick up on new sounds if you are going to be able to converse anyway and you should definitely learn your target language's orthography to be a proficient reader/writer.

That said, I enjoy learning languages in addition to studying (comparing, contrasting, etc) and have found the IPA helpful to give me a leg up on that. Therefore, I recommend the IPA for polyglots and linguists.