Might be good to see if it still works fine after changing the baudrate [eg, software that experimentally tries to up the baudrate using the AT command - is it still possible to recover?] Does changing the baudrate actually change anything?
Try connecting to it from different systems. Specifically see if you can find some old card that only does 802.11b [eg, the wireless thingy with my Palm Tugsten2], and check that it works with b/g and b/g/n devices from different vendors.
Test the actual data rate, compare to the sample rate when connecting via USB or bluetooth.
I also specifically care that it works with more OSs than just windows. Check that OSX and at least one variant of linux can work with it. Ideally Tiger 10.4ppc as well as newer intel ones.