Summary from Social Media Buzz:
Strengths: SEMrush‘s data includes sites of all sizes, a list of key phrases and rankings for those terms — and provided the most accurate data of all the tools we examined.
Weaknesses: The data were still imperfect. Customers must pay to get full data lists. And the data is only for Google traffic.
Accuracy: The data were not perfectly accurate, though generally speaking SEMrush did not miss the mark for any of the sites we tested the way a number of the other tools did. In the end, the data were surprisingly accurate. As with some of the Google data, the information reported is just the Google search engine traffic, but this is our main area of focus and was quite accurate when drilling down into that specific area of traffic within analytics.
How to best use SEMrush: Although imperfect, this tool came the closest to providing accurate data that I would, at least with a word of warning, be willing to share with a client about potential expectations or about where their competitors’ traffic may be. Most importantly, the add-on options and ability to see the keyword lists and how the competitor ranks for these terms is extraordinarily appealing.