My first suggestion about Isla (though I'm sure it's too late) is to go during the week and early. You'll have a much more relaxing time with attentive service. On weekends, the restaurant tends to be cramped and noisy with and the service a bit stressed out. Not good for the digestion, to say the least.
Another appetizer I liked were the pinones--plantains stuffed with ground beef. As for entrees, go for the specials. Once I had huge, moist cumin-crusted scallops on mashed potatoes. Another time a crab "souffle" though it was really lump crabmeat on top of risotto. Those specials were much better than what my companions ordered from the menu, though the food isn't bad. Pass on the chicken fricasse--a flavorless mishmash. Their ropa vieja isn't bad, and their filet mignon is quite good. Have a mango caiphrinha, but most of all, have fun!
We found the appetizers at Isla to be stunning- particularly their assortment of ceviches (not to be missed) and mussels in a rich smoked tomato sauce, but we sampled 3 or 4 others as well, and the appetizers were far superior to our entrees. It was several months ago, so I'm blanking on the specifics, but after really fabulous appetizers (and killer mojitos), we were excited for a great meal, and then found the entrees plain and misconceived in some cases (I had a boring sea bass...). Dessert were sweet and comforting (there was a really yummy one involving gingerbread and a good "cafe con leche" flan).
So I would suggest pigging out on appetizers, washing them down with delicious cocktails, and then finishing up with a dessert or two. That's what I would do if I went back.
Hi, I agree with Elaine's assessment. I've been there 3 or 4 times, and the apps (esp the ceviche)were spectacular. Splurge on those, as in my op, too, the mains were less consistent. It's a neat place, but bring earplugs if you don't like a din. This place is *really* loud. Here's the link to my post in Oct 2000
btw, look out for the 4 dead-ringers of the main female characters in Sex and the City. They were there the last time we were there. Really fascinating. And, oh, the cocktails are very good indeed.