There are two key issues that (unfortunately) forced me to choose another option. I didn't want to because this cart IS so very promising with tons of potential.
1. There needs to be an allowance for more than one product image. Of course a merchant can always find a way to creatively do this, not a big problem, really.
2. This one is big -- to me :)-- The user registration at checkout forces the customer to leave the site, and then confirm their registration after they have shopped and gone half way though the checkout process. I think the entire point in having a seamless solution like this is so that it's seamless. I personally like the registration process but a simple continue checkout button, allowing them to complete the order and get their info afterward would help with cart/sale abandonment.
It's a good free feature and I do see the longterm potential.