Every photographer (professional and otherwise) has always told me that "the best camera is the one you have with you." Having great equipment is all well and good, but in the end, knowing how to compose a shot is the single most important part of photography. (Protip: Turn the grid feature on, and Google why you should use it.)
Personally, I would much rather have a small, multi-purpose device that takes decent photos rather than having to lug around something larger that does literally one thing. So yes, I'd rather take my iPhone and use that for photos. And just about every iPhone can take really great pictures, so I'd say they'd be good enough.
At the very least, make sure to make use of the Photopass photographers, even if you didn't buy Photopass. You never know when they'll take a great shot that you missed, and you can always buy (at a premium, of course) after the fact. Just remember that for the most part, Photopass photogs are not "professional" in the sense that we think. They're usually enthusiastic amateurs with decent equipment. But every so often, they get a great shot.
One last tip ... if you do decide to use your iPhone, consider paying a few bucks for a third-party camera app. I used
Camera+, and it has some outstanding features for only $1.99. The Stabilization feature alone is great ... it waits to take the picture until the gyroscope/accelerometer says that your hands aren't shaking. It's saved a LOT of pictures for me.