This article in BN/DeStem reveals that Paypal has 1 million Dutch customers. The article compares the features of the bank-based iDEAL payments system and Paypal. Essentially the main difference is that Paypal has international payment/acceptance features (with customers/merchants being able to both received and pay) while iDEAL serves mainly domestic Dutch transactions allowing customers to pay merchants but not to pay each other. Furthermore Paypal is fully webbased, with a lot of software controls to secure payments, whereas most banks secure the iDEAL payment with a bit of hardware or a separate sms-verification effort.
If the personell ads were something to go by the Paypal efforts should not be underestimated. They will be building a base here and will remain to have their international and peer-to-peer advantage, even if iDEAL would become a European standard. So there appears to be quite a sustainable advantage for them.