I use an iPhone for most of my photos too. I am going to buy one of those lens kit attachments that come with a macro and wide angle. Focusing up close with an iPhone can be tricky sometimes. Using an app other than Apple's Camera app could help. Several, including Camera+ and Camera Awesome, let you adjust focus and exposure separately. Apple's Camera app doesn't do that. No matter what app, auto focusing is not as reliable up close. It is best to tap on the screen to focus.
One thing I like most about the iPhone is color rendition. I like it better than my Canon S90 point and shoot and my Olympus E520 DSLR of which both were top rated in color when I bought them.