As a customer, I hate 3D secure. When I get that shit thrown at me, I often just head over to Amazon and buy the same item there. Even if it is more expensive.
Reasons:
The 3D Secure form always looks so unprofessional it makes me shiver.
It often is loaded in an iframe so it could come from god knows where.
Often it plain out does not work. It aborts the transaction with "Transaction aborted" or something like that with no further info. So I sit there thinking "Uhm.. what now? Is my password wrong or what?".
Why would I input even more of my data into your damn form? The more data I give you, the easier you can mess with me. Now my CC card number and verification number is not enough anymore. Now you want my 3D "secure" password. What do you want next?