At WWDC2010 the long-waited Apple iPhone 4 (16GB and 32GB version), the 4th generation of iPhone, was released this June, together with iPhone 3GS (8GB version), after the success of iPhone and iPhone 3G. Please see Apple iPhone 4 review for more details.

1.  Apple iPhone 4—Appearance

(1) IPhone 4—Keys Layout
IPhone 4 has some changes in layout of SIM card slot, volume keys and dual-microphone. Dual-microphone with noise-suppression function is another improvement in appearance, which greatly improves the speech quality. And the secondary microphone can be used as a receiver for improving sound quality in FaceTime.

a. Left: Previous single volume key is divided into 2 individual keys, together with one mute key are on the left body
b. Right: The SIM card slot is moved to the right side of iPhone.
c. Top: A 3.5mm stereo headphone mini-jack, a mini microphone and a sleep-wake key are present in order on the top.
d. Bottom: There is a speaker-like microphone, a 30-pin dock connector, and a built-in speaker on the bottom.

(2) IPhone 4—Retina Display
The greatest improvement of apple iPhone 4 is the 3.5″ wide screen with latest Retina display offering an ultra-clear 960x 640 screen resolution and 800:1 contrast ratio. The latest Retina display with 326 pixels per inch quadruples the panel density for wide viewing angle and superb color, so whites are brighter, blacks are darker, and the image in web page, games and movies will be more brilliant. Besides, Retina display is power-saving. The built-in ambient light sensor and LED backlighting will adjust automatically the brightness of the screen to save power.

(3) IPhone 4—Durable Tempered Glass & Seamless Surface
The apple iPhone 4 gives us an elegant and sturdier feeling compared to its predecessor, owing to seamless surface without a gap to collect dirt & dust and smooth piano finish in the front and rear of iPhone 4. The sturdier felling comes from the scratch-resistant and durable tempered glass often used in helicopter or high-speed trains.

(4) IPhone 4—Antenna
The other studier felling of Apple iPhone 4 derive from the stainless steel band surrounding the side. To our surprise, actually the antennas is integrated with the stainless steel band, the left border for Bluetooth, Wi-Fi and GPS, the right side for UMTS and GSM, instead of being hidden inside the body.

(5) Ultra-thin Body
This distinguished room-saving design of Antenna makes iPhone 4 an ultra-thin phone. With the thickness of 9.3mm, iPhone 4 looks like an elegant matchbox, which is 24% thinner than iPhone 3GS (12.3mm).

2. Apple IPhone 4—Features

(1) IPhone 4—Hardware
a. Processor & Memory
Apple iPhone 4 sports 1GHz Apple A4 processor, which is power-saving, and larger built-in memory (up to 512MB) than iPhone 3GS and iPad. The upgrade of hardware ensures the better performance.
b. Battery Capacity
The upgrade of iPhone 4 hardware brings better battery capacity, which allows up to 300h standby time, 7 h (3G)/ 14 h (2G) talk time, 6 h (3G)/ 10 h (Wi-Fi) , Up to 10 h Video playback, 40 h Audio playback.

(2) IPhone 4—Three-axis Gyro
The new three-axis gyro and accelerometer of Apple iPhone 4 provide 6-axis motion sensing, making operating experience close to reality. The new three-axis gyro can be widely used in many ways, such as testing slope and displacement distance.

(3) IPhone 4—5MP Camera + LED flash+ Front VGA Camera
Besides the 5MP rear-camera supporting 720P HD video recording (1280×720), iPhone 4 brings in front-facing camera for video chatting in FaceTime and LED flash for better capturing effect.

(4) IPhone 4—Support Micro SIM Card Only
For saving room for battery, iPhone 4 only support specialized Micro SIM instead of standard SIM card, which will be inconvenient for most users.

(5) IPhone 4—FaceTime Video Calling
You can enjoy a high quality FaceTime video calling by clicking the FaceTime icon with Wi-Fi connectivity on condition that the calling and called party are iPhone 4 users.

By the way, the limitation of WiFi connectivity in FaceTime video calling is temporary, and we estimated iPhone 4 users can use FaceTime function via 3G in 2011.

Furthermore, Apple Company hoped that FaceTime technology, allowing multiple open standards, such as H.264, AAC, SIP, STUN, TURN, ICE, RTP, SRTP, would be industry standards in the future.

(6) IPhone 4—Connectivity
IPhone 4 offers 3.5mm headset jack, 802.11b/g/n Wi-Fi, GPS navigation, digital compass and Bluetooth 2.1+EDR. Besides, iPhone 4 supports UMTS/HSDPA/HSUPA (3G) and GSM/EDGE (2G) network

3.  Apple iPhone—Summary:
Comparing to the previous iPhone 3GS, Apple iPhone 4 has so many upgrades in performance and appearance, which will bring you pleasing experience and surprise.

(1) Pros
9.3mm ultra-slim body
Retina display with high resolution
Scratch-resistant and durable tempered glass
5MP camera with 720P HD video recording
FaceTime video calling via WiFi connectivity
Three-axis Gyro+ accelerometer
Power-saving and high-speed 1GHz ARM Cortex-A8 processor
512MB built-in memory

(2) Cons
Controversial antenna problem
Support specialized Micro-SIM card Only

4. Apple iPhone 4—Specification

3G Network: HSUPA (850, 900, 1900, 2100 MHz)
2G Network: GSM (850, 900, 1800, 1900 MHz)
Size: 115.2×58.6×9.3mm, 137g
Display: 3.5-inch widescreen Multi-Touch Retina display (640×960 pixel resolution at 326 ppi, contrast ratio: 800:1, 500cd/㎡ brightness), scratch-resistant surface, multi-touch input method,
Sensor: Three-axis gyro+ accelerometer provide 6-axis motion sensing, proximity sensor, ambient light sensor
Connectivity: GPS, 802.11b/g/n Wi-Fi (802.11n 2.4GHz only), Bluetooth 2.1 + EDR wireless   technology, 3.5mm headset jack
Other Features: Facetime, GPS
Memory: Built-in 512MB and 16GB or 32GB versions available
Camera: 5MP autofocus camera (2592×1944 pixels) with LED flash (Video recording, 720p HD up to 30 frames per second with audio) and a secondary VGA front camera, geo-tagging
OS: iOS 4
Processor: 1GHz Apple A4 processor
Battery: Rechargeable lithium-ion,
Talk time: up to 7 hours on 3G/ up to 14 hours on 2G, standby time: up to 300 hours
Internet use: up to 6 hours on 3G/ up to 10 hours on Wi-Fi
Video playback: up to 10 hours
Audio playback: up to 40 hours