It's not terribly good. But it also won't outright kill her like some foods out there.
I would change it... slowly. If I'm recalling correctly, she's been with you about a week? If that's the case, you can start adding in a little bit of a higher quality cat kibble. You'll want to aim for about 1/4 new food and 3/4 Iams for a week before increasing the amount of new food to old.
Some people will choose to stop there; ie, 50% high quality kibble to 50% less good food.
Personally, I'd find a second high quality food then start replacing the Iams... something like:
Week 1: 25% new high quality food #1 and 75% Iams
Week 2: 50% new high quality food #1 and 50% Iams
Week 3: 50% new high quality food #1, 25% new high quality food #2, and 25% Iams
Week 4: 50% new high quality food #1 and 50% new high quality food #2
Lots of people will stop there. And that's a pretty decent place to stop. I add in a third kibble. I like that because if there's a problem with one (recalled, goes stale, runs out, hedgie's tastes change and they don't want it anymore, etc...) then I have two kibbles to fall back on.