I have an iPad and an iPhone, and I can't see why having a larger phone would be an advantage. The phone is still too small for me to use as an internet device, except in an urgent necessity; and my iPad is the perfect size to do that . The phone that I have fits perfectly in my purse, and being larger would not help with anything that i use mine for. I just use mine for phone calls, taking pictures, and the occasional text message.
My daughter like some of the other new benefits that it has; but she didn't want a phone that was larger either, and even the smaller of the two new ones is larger than the older iPhones.
The new ones have a lot more memory storage, and will also have the capability to be used at stores for paying for purchases.
This is what I can see as the greatest benefit for the new phones. Since you do not need to use a credit cart to pay for something, the clerk (or anyone else) never sees your card, so there is no chance of the information being stolen like happened at Target, or just recently at Home Depot.