There are a wide variety of smart phones on the market. The Apple iPhone is up to its fourth incarnation and every mobile phone manufacturer has released at least one variant. The reason the innovation most impresses me is because of how useful they are. Many incorporate more features than a regular PDA and are essentially a hand held mobile computing device. Some of the features that are most impressive to me are things such as GPS navigation capabilities, 3D graphic acceleration, the capacity to read electronic books and on screen keyboards. All of these things coupled with 3G connectivity for mobile Internet browsing and operating systems that can run various other applications really make smart phone technology shine.
My first cell phone had a simple LCD screen that had two colors, much the same as a basic calculator. The screen size was tiny, it allowed for no more than two lines of text. Scrolling through phone numbers was a massive hassle. Many smart phones now offer fairly high screen resolutions and touch screen capabilities. This is on a screen that virtually takes up the complete area of the front of the phone. Many offer streaming video and video phone support. Smart phones are quickly becoming more advanced than a regular home phone (and in most cases are).
Because many companies who exclusively released computer components have entered the smart phone market, smart phone innovation is moving at a rapid pace. New features are being packed into a tiny handset and smart phones are becoming cheaper and cheaper. Many companies have moved their cell phone development processes strictly into the realm of smart phone development. Eventually you may have trouble finding a cell phone that only will allow you to make and receive calls on the go. This is not a bad thing.