I love PayPal for eBay - I don't think I'd use it anywhere else though.
As a buyer I will only buy on eBay using PayPal - it's quick, and if the PayPal protection shield is showing, I am protected against fraud and will get my money back. It is by far the safest way to buy on eBay.
As a seller, I don't have to wait for cheques to arrive and then clear. Provided I follow the rules I know I am protected.
Yes, there are fees. But I sell a lot of higher value items and it means my buyers can use their credit cards if they want to. I think the fees are reasonable, especially as I would have to pay petrol and parking fees to deposit cheques.
PayPal users must understand the rules, or they could lose out. But by being careful and complying it is very safe.
I know I would lose a lot of sales if I did not accept PayPal.