That’s a very vague question, and has already been discussed at great length on this forum. You can read a couple of recent discussions here:
or do a Search on the forums.
You’ll get a better answer if you can be more specific – what exactly do you want to be able to achieve with this SEO tool?
Please note – if you can’t be more specific in what you’re asking for and this thread starts to become a repeat of ones we’ve already had umpteen times before, I’ll close it. We’re looking for useful and constructive replies, please!