Here are my impressions after purchasing the iPhone4:
(1) WHERE YOU PURCHASE YOUR iPHONE MAKES A HUGE DIFFERENCE - Avoid making a purchase at a cell phone store, their iPhone stock is the bottom of the barrel. Your best option is an actual Apple store if you live close enough to one; otherwise, Apple.com is good. please note that an Apple retail store and their online store are two different animals. If you make a purchase online, you need to return online for a refund.
(2) REFURBISHED iPHONES ARE ONLY AVAILABLE FOR SALE ONLINE - you can get anywhere from $50-$100 off the original price if you chose a refurbished iPhone but the warranty is shorter then a new one. These options might include wear so be sure to read all the details. Be very careful, you might save money upfront but with all the internal antenna issues, you might end up paying much more in the long run.
(3) SIZE DOES MATTER - Whatever storage size you choose, that's it because the iPhone does not allow cards or usb ports for storage.
(4) YOUR iPHONE WILL WORK AS ONLY AS GOOD AS YOUR SERVICE PROVIDER: your cell phone coverage, reception and internet capabilities will depend on your carrier. In the States, AT&T provides worse service then it's competitor, Verizon,but is the only one that lets you talk on the phone and allow you to use the internet. The phone you purchase is locked in to a specific carrier, there is no changes service providers unless you buy a new phone.
I purchased a new iPhone 4 / 32GB online and had problems from the start. The volume of the phone was too low on calls no matter how I adjusted the settings and sometimes, it would not find allow internet access at home even though I have a wireless network. Placing a call to their customer service was easy and technical support is free for the first 90 days. It was determined that I had a bad internal antenna, which seems to be fairly common. I was told to make an appointment for the Genius Bar (ego much?) at a nearby retail store and that they could get me a new iPhone. Not so fast. My Apple Genius explained how the online and retail stores do NOT operate as one. I could trade in my new iPhone 4 for a refurbished one. Ouch. But as the Genius pointed out, the refurbished one worked and the brand spanking new one did not. My replacement has the same 1 year warranty so I'm keeping my fingers crossed it will last.
Knowing this why would I purchase an iPhone 4? For the convenience and the apps of course! Although Android offers plenty of apps and keeps getting more, the iPhone blows everyone away in this department. I have had the iPhone 4 for ten months months and I love the features but still have minor picks. For one, iTunes automatically synchs all new apps every time I connect my iPhone to my pc, no matter how I set it. Annoying. Also, it can take up to several minutes to access certain media apps (i.e. Netflix) but I understand iOS 5 should help speed things up. Once you experience the great features of the iPhone 4, it's hard to go back to other phones. I never understood why people were such avid apple fans until I purchased this phone. It makes my life easier and more fun which makes it worth every dollar.