Outdated and limited to amazon.com Rated 2 out of 5 stars
The addon seems to only support amazon.com, which is less than optimal if you're frequently "Amazon hopping" between different languages/regions and often a referral code will only work for a single Amazon instance, so you can't just use the same one for all of them.
Also, it seems like it doesn't support e10s, but it also hasn't been updated for years. (Even the listed official website no longer works – seems like it's now a Japanese domain squat page… ?)
Rated 5 out of 5 stars
works great for quickly making purchases to donate to my favorite podcasts