I am sad to say, that my experience with PMP's Paypal transactions is anything but possitive. After errors creating levels and figuring out that every field needs to have a value of 0 even though the checkbox says don't use those fields I was finally able to get to a point of testing the plugin. I then found error after error:
1. Free level raises error as it tries to convert a "" string into an integer when there is no discount code.
2. When testing PayPal express, I noticed there were no amounts shown in Paypal for the re-occurring payments are not reflected anywhere. Upon accepting of the payment I get re-directed back to the PMPro in my site and the confirmation shows a message of "The PayPal Token was lost". On checking the url I can see the review and token value are present. I then proceeded to check the order table and found there was not even a record for the order present.
3. Then testing PayPal standard I noticed that there are still no orders records created.
On investigation I noticed the insert statement for the pmpro_membership_orders was unable to find the UserId and the CertificateID. these fields are both being populated with "" and this causes an error when trying to convert to int.
I am also testing out another membership/subscription plugin, it has none of these problems.