No, you can use it just as a broad indicator as it is based on traffic from users who have alexa toolbar installed.
No, it can give you a vague idea but it is in no way accurate. it is so easy to manipulate your ranking that you can infer very little from what it tells you.
Although alexa have problems, but it is after all still the largest third-party traffic assessment agencies.
Alexa can give you a rank based on visitors who are using alexa or its affiliate's tool bar. its not an accurate method. Use Urchin or GA.
Agree. I suppose Alexa rank is not demonstrative at all. You'd better use another traffic tracking service.
Alexa is best to study your competitors' keyword density, and to find keywords they're not ranking high for. That makes it valuable, but maybe not so much for measuring traffic.
Alexa is completely useless. I have my raw apache logs, so I can decide what's accurate or not. Google analytics is pretty spot on. Doesn't Alexa use the toolbar for tracking; who on earth even uses that?