As far as Eukanuba food is concerned, it's not the worst but by far not the best. Some feed it and swear by the results, some don't. You have to determine what is the best match for your individual dogs. There is a sticky at the top of this section with links to some of the more preferable commerical food manufacturers--many will send you samples and coupons to try.
As far as the Iams company, many don't support the company (at least in in the form of buying their food) because of their involvement several years back w/ cruel animal testing. Iams didn't conduct the research themselves, but hired an outside company to perform testing with the products they manufacture--*some* testing is required, but NOT in the manner in which the company carried it out.
Iams cut ties w/ the company in early 2003 after the conditions of the animals were made public.