Here's another interesting article about the trash island in the Pacific (1 of 5 around the world).
10 interesting facts about the Great Pacific Garbage Patch
There's a close up picture of the floating plastic and it's mostly chunks, not bags, but it sounds like the fragile plastic breaks down into small pieces quickly. They say 74% of the diet of sea turtles within the GPGP consists of plastic debris and 46% of the island is fishing nets. They also say they are going to have 90% of the floating stuff cleaned up in the next 15 to 20 years but most of it isn't floating.
I can't guess to the accuracy as it is written by Eradicate Plastic, they may be biased.