I think based off hardware, iPhone 4 is easily the best. All the features I wanted is now in this phone. It was the iPhone I dreamed about three years ago and it finally came true. But so far, none of us have really tested it for months to know if it is buggy or not. It also the most scratch resistant of any of the iterations. No chrome bezel. No plastic backing. But from a software standpoint, it may never match the first iPhone or the iOS 2.0 that allowed the App Store. More of the same. I won't get a completely new revolutionary experience like what I felt in 2007 and 2008. The UI has hardly changed since I experienced jailbreaking prior to 2.0 already when so many apps were still free. The hardware, features, and design is where it got improved and refined.
I'm predicting the iPhone 4 will go down as one of our all-time favorite iPhones. Perfection refined, inside and out. First off, I love the number "4" because my birthday falls on that number. One of my lucky numbers. No 4G or 4GS. Just call it iPhone 4. More simple. "The iPhone 4 Life." Second, I really need a new phone as my current one is crapping out on me after two years with the battery. I can now get 40 hours of music and half a day of talk time on 2G instead of the 3-4 hours from my Nokia N82 back then. I was perfectly eligible for an upgrade this year, and the iPhone 4 is now becoming a life saver. My old phone just isn't dependable when it comes to battery and the UI just sucks.
Next year, we could be dealing with very minimal upgrades. Maybe a bump in MP for the camera which is something I don't really need. Taking pix at higher the MP just takes up more space. They will boost in GB as usual. Perhaps come in different colors since this 4 version offers the first all white iPhone. Adding Xenon flash is just impossible for it to make a phone thin like that. Bigger screens and a 4G network could kill battery. They could even cheapen the look and quality of the materials like they did with the 3G and 3GS after the aluminum back of the original. And look at the design of the 3rd gen iPod (classic) and the "fatty" iPod nano. Unique. I hate if Apple goes back to the scratch prone chrome and curved "plastic" back. Finding the right balance of features, design and hardware without sacrificing battery is a tricky thing to do. They could also have the CPU underclocked to conserve battery before increasing speeds again in the next two years where the battery life takes a hit.
Looking at pattern, I expect the next biggest leap happens by 2013. This iPhone 4 can still hold its own by then even as a backup phone. There is just something perfectly balanced and refined about the iPhone 4 that when they try to revise the iPhone next year, it may not really be all that better. This one feels special. Like certain Air Jordans that stood the test of time or the original 60 GB PS3 or fatty PSP before Sony cheapened out. The iPhone 4 feels special and enduring. I'll probably still feel content using this one even after my two-year AT&T contract is up.