cpdpurcell:
NO!
Don't go thinking that and applying. When they say 15 months interest free it means that there is a special period of 15 months where you can purchase items without having to pay interest on them IMMEDIATELY.
However, you only get 59 DAYS interest free from the point of each purchase.
So if you buy something within the 15 months you get 59 days to pay it off in full without incurring interest.
If you buy something after the 15 months then you are charged interest from the start.

You have completely misunderstood the offer.
Almost every credit card gives you 59 days. This one is totally interest free up until the end of the 15 months. So if you buy something after 3 months, you have 12 months interest free and so on.
You have to pay the minimum payment every month, and clear the balance at the end of the offer to not incur interest. The end of the interest free period is shown on every statement so you can clearly plan ahead. The interest free period does not cover cash advances or balance transfers.
After the end of the 15 months you get the same period interest free after buying the goods that you would expect from any credit card, usually 59 days.