Yeah, that is one thing it can do, but it's not the only thing it does. I'm not sure how to get my point across well but, just because it gives you the wrong answer 25% of the time doesn't mean it's useless. In whatever you ask it to do, it often gets you most of the way there as long as you know how to correct it or check its work. The ability to ask specific or follow-up questions when learning something makes it invaluable as a learning tool (if you're teaching yourself that is (ie. If you're a university student)). It's also very useful when brainstorming ideas or helping you approach a problem from a different angle. I can also ask it questions that are far more specific than what a search engine would get me.

It really comes down to if the human operator knows how (and when) to use it properly.