Not great but free.
One big problem is that it won't cancel a known fraudulent deal before the transaction takes place. So you can end up with Paypal fees after you reverse it.
Simple fix I think.
Doesn't work well.. It does not filter accurately. Keeping it just because it's free..?
FYI, this app is no longer supported by Shopify. It had worked fine until today, but just caused a false failure and automatically voided a returning customer's order for unknown reason. After an online chat, the Shopify tech & I agreed it was best to remove it.