Seriously, if the sales guy for cameras is telling you to stick with your existing iPhone, then that right there should be telling you something significant!
Save your money on the camera and instead buy a Gorilla Grip tripod for your iPhone from Gearbest or DealExtreme or AliExpress or any of the other Chinese online sellers for no more than $2 in a flash sale. Also buy a Xioami Power Bank 2 and get yourself a silicon case for it too so it doesnt scratch your iPhone. That'll be another $20.
Then jailbreak your iPhone and install PhotoRes app from Cydia. That will open up a whole world of new photo settings within your iPhone you never knew existed that Apple choose to hide from users in line with their walled garden software environment.
I only have an iPhone 4S, but with all the above, I can take photos that are way beyond my former P&S Ricoh R5's capacity. I only tossed my Ricoh in the bin a couple of weeks ago in fact after finally accepting it had no further practical use.