I have installed it and tested rankings on few sites.

PROS:

1. The plugin performance is extremely good.
2. Lightweight and easy to use. (12KB)
3. Does not consume more data, compared to Alexa official tool.
4. Loads the metrics fast and user-friendly.

CONS:

1. It has only one con, when i tested the country rank, the plugin showed 569, while on Alexa site, the country rank was 562.

Cheers,
kksilvery.