How good is Natural Balance L.I.D. Limited Ingredient Diets Green Pea & Duck Formula?

Peas, Duck, Duck Meal, Pea Protein, Canola Oil, Flaxseed, Natural Flavor, Calcium Carbonate, Choline Chloride, Taurine, DL-methionine, Natural Mixed Tocopherols, Zinc Proteinate, Vitamin E Supplement, Niacin, Manganese Proteinate, Copper Proteinate, Zinc Sulfate, Manganese Sulfate, Copper Sulfate, Thiamine Mononitrate (Vitamin B-1), Vitamin A Supplement, Biotin, Potassium Iodide, Calcium Pantothenate, Riboflavin (Vitamin B-2), Pyridoxine Hydrochloride (Vitamin B-6), Vitamin B-12 Supplement, Manganous Oxide, Sodium Selenite, Vitamin D-3 Supplement, Folic Acid

Peas as first ingredient??? 

Is this ok?

An alternative simliar food is Nature's Variety Instinct Limited Ingredients. Peas are the second ingredient in the dry food.

I have no idea what the purpose of peas is Protein? Filler? Something to hold the food together?

Peas are considered non-allergenic or at least, less allergenic than other ingredients. It is also in some hypo veterinary foods. Some clienta whose pets have sensitivities to food but can-t afford the vet foods, I recommend Natural Balance to and their cats are doing well. For cats with true food allergies, I would recommend the vet hypo diets.