While I don't consider Iams to be in the same 'league' as Innova or Wellness, I do feed Iams to some of my cats. Mew has a very sensitive stomach and was eating Natural Balance Venison and Green Pea. After the food recalls, it was off the shelves for so long I had to find something else. I tried Royal Canin sensitive stomach and she went back to chewing holes in herself and vomiting several times a day. I put her on Iams senior and she hasn't vomited once and has stopped the mutilation. I'm not going to switch her again, so she'll be in Iams for the rest of her life.
Lemony can have very stinky poop, and Iams original adult is the only food she can eat that keeps the smell to a 'normal' level. To help simplify a bit, Eggs eats it as well. Tux and Smeg are on urinary vet food and kittens eat a combination of Wellness kitten and Iams kitten. They were eating just Wellness, but it's too expensive for nine ravenous kittens. I was going through three bags a week!
I have tried many foods for my dogs, had them on homemade raw, premade raw, dehydrated, you name it. The only food they all can eat, and all do fabulous on is Nature's Variety Raw Instinct kibble. I tried Innova Evo but found it made my dogs fat and have dull coats. I think Nature's Variety makes a cat version as well.
To me it depends more on how you pet does on it, than how high quality the food is. If they're vibrant, shiny, thin, healthy and bursting with life, than it's a good food choice for them.