My husband and I spent an afternoon at Isla Ixtapa in Nov 2007. There are two swim beaches and a snorkeling beach. The waves were starting to pick up at the snorkeling beach, which faces the Pacific so we did not snorkel.
The swim beaches are very small, good for children and perfect for a dip to cool off.
We sat at the restaurant 7 Mares, because I had seen it in the Ixtapa/Zihau forums. The service there was great! The owner came out to greet us personally and brought us each a drink on the house.
Every restaurant will try to get you to sit at their tables. Take a look at the menu...a lunch entree for around 70 to 90 pesos and beer for 20 pesos is reasonable. Some will have 2 for 1 drinks from noon to 5:00pm.
The beach vendors selling necklaces and such will usually go away after a polite "Gracias, no." Others will start spreading their wares out on your table and require a firmer "nada" before they leave you alone.
There are two piers to the main beach on the left and a smaller beach on the right. The snorkeling beach is on the back side of the island on the right. There is a foot path over the hill connecting the two swim beaches.

