The quality of the extension and code are quite good... we didn't have to correct any errors when implementing it and there were no violations of Magento development best practices that we saw. I would love for the reports to be more customizeable in terms of mapping cost and revenue to the reports themselves.
You Should give it a try... In 3 clics, you have the most valuable information about Your sales and profitability ! The export feature is also very usefull to continue analysis on a spreadsheet
I highly recommend this extension !