As the name suggests iPhone 4 belongs to the fourth generation of iPhone. It also runs on the same operating system like its descendants i.e. Apple’s iOS. It has decked with some spectacular features like video calling, media consumption; retina and multi touch display etc. The new splendid design includes an uninsulated stainless steel frame that act as the device’s antenna. Furthermore, the latest release of iOS 4.2.1 operating system offer added functionalities such as AirPlay and AirPrint. Following are the noticeable features of iPhone 4:

Retina Display: The iPhone 4 has a 3.5 inch display with a basic resolution of 960 by 640 pixels making the text extremely sharp and graphics incredibly vibrant. Brilliant color and contrast is IPS technology usage.
Video Calling: The front-facing camera is specially installed for serving video calls enabling video conferencing anywhere and anytime.
Engineered Glass: In iPhone 4, two shiny panels of aluminosilicate glass contains all the advanced technology between them. The Aluminosilicate glass is the same type of glass used in the windshields of helicopters and high-speed trains. And the best thing; it is recyclable.
Stainless Steel Band: iPhone 4 also has a Stainless Steel band which is five times stronger than standard steel providing amazingly thin refined design and extraordinary structural rigidity.
Apple A4 Chip: The A4 chip developed by its engineers can easily perform various complex jobs such as multitasking, editing videos, and placing FaceTime calls.
Gyroscope & Accelerometer: iPhone 4 consists of an integral three-axis gyroscope; which when joined with the accelerometer, makes iPhone 4 competent enough to offer advance motion sensing features for an enhanced gaming experience.
Camera LED & iMovie: The iPhone 4 camera with a backside-illuminated sensor shoots lovely 5-megapixel photos and astonishing HD videos even in low-light settings. The en suite LED flash not only works as a flash during picture capturing but also stay on to light up the scene while shooting a video. Moreover, it is ideal for making FaceTime calls and shooting self-portraits.
Search Engine Bing: Though Google will still be the iPhone’s default search engine but Yahoo and Bing-powered searches will also be available as options.
iBooks for iPhone: Apple enables its users to start reading an iBook on an iPhone. They can now download purchased books to all their supported devices without any extra charge.
iAds: iAds is Apple’s latest in-application advertising platform. It provides an interactive experience without causing users to leave apps or lose work unlike traditional banner ads that drive out users from applications into Web browsers.
Mic & Speaker: iPhone 4 has two mics contrasting most phones which have only one microphone. The main mic and the second mic offer phone calls, voice commands, memos and FaceTime calls. They also enable dual-mic noise suppression that helps in making each conversation a quiet one.

Advantages of iPhone 4 over iPhone 3GS are as follows :

Stylist new design with elite glass panels
1GHz Apple A4 platform is faster than ever before
Now reaching 512MB which is double the RAM amount
Three-axis gyro sensor designed for unmatched motion control
5MP AF camera with backside illuminated sensor and LED flash
Quad-band 3G with HSDPA and HSUPA
Front video-call camera for making FaceTime calls
Have 802.11n Wi-Fi support
Wider viewing angles with 4x the resolution & contrast ratio
Camcoder shoots 720p HD videos at 30fps
Active noise cancellation with the main mic
Superior battery life