The 'problems,' and I do mean to emphasize, 'problems,' is:

1) It is owned by Ebay. If you get paid through Paypal and there is a dispute between you and the platform on which you sell (aka Ebay) who wins the dispute? You? Not really Paypal is owned by Ebay and so will yield to whatever Ebay says vetoing any selling rights they may have given you whenever they feel like it.

2) Paypal isn't a bank. I'll give you a scenario. If your bank decided to at random remove payments from your bank account putting money 'onhold' until you showed them proof of what the payment was for do you think that would be ok? Paypal does this, without reason, simply as they say to keep Ebay and Paypal a safe market place to consumers. But it happens all the time and at random. Paypal is a private corporation and as such doesn't have to follow legislation that banks must follow by law.

3) Paypal used to be an option to pay on Ebay but you could also sell and be paid by moneyorder, cashiers check and other methods. Now you are forced to use Paypal on Ebay. You may take no other payment except credit card through a merchant account (which most people do not have and which is much more expensive than paypal).

4) If you ship items to countries that do not use electronic scans that post online in their postal services and someone enters a dispute saying they didn't receive their item you will lose your money. Even if you file a dispute with your postal service and they confirm with that countries postal service that it was delivered and you receive documentation Paypal will not accept documentation and will not bother to contact the customer. They will allow the customer to keep their items and the money, they will only accept the online electronic stamp.

There are many more issue and I expect this list to grow so check back often.