This blocked some orders from being linked to my affiliate account.
This is clearly an error that doesn't appear to be common, however it has cost me a fair bit in commission.
As soon as I uninstalled it, my normal daily number of orders appeared again almost instantly. In my opinion, it seems like too much of a risk to install for the sake of having a few extra countries - if it means you cannot feel sure that the links are working as they should originally.
This is not to take anything away from the plugin or the author - I think it's great, and he's doing a good job, but I did always feel a sense of worry as to whether or not it was working properly and this was clearly reflected in my experience of using it.
I had a look round for other similar plugins and it appears the author is in a battle with another plugin of a similar title called 'amazon-affiliate-link-globalizer' of whom he accuses (in reviews) of fixing bugs in that plugin to change your IDs to his completely, so I would NOT use this one either.
Although this is not a problem, it's unfortunately a reflection on authors of both plugins and when dealing with something of this nature, I'd like to feel the plugin is really working and that I can trust the authors, not read both of them slagging off each others plugins.