Specification Iphone 3G

Specification Iphone 3G - As to whether the features and specifications of Apple iPhone 3G compared to its predecessor, the Apple iPhone? 
what are the advantages and disadvantages of Apple iPhone 3G? 
why iphone 3G is worth less?

Features and Specifications Apple iPhone 3G
 
Network         : GSM 850/900/1800/1900, 
                       HSDPA 850/1900/2100
Dimensions    : 115.5 x 62.1 x 12.3 mm
Weight          : 133 grams
Display Type  : Touchscreen, 16M colors
Screen Size    : 320 x 480 pixels, 3.5 inches
Ringtones      : Polyphonic, MP3
Vibration       : Yes
Phonebook     : Yes,
                      unlimited storage, 
                      depending on storage, 
                      Photocall
Memory Slot   : No
GPRS             : Yes
HSCSD           : No
3G                : Yes, HSPDA
WLAN            : Wi-Fi 802.11b / g
Bluetooth       : Yes, v2.0, headset support only
Infrared Port   : No
USB                   : Yes, v2.0
Operating system:  iPhone OS 2.0 (1.2.0 - Build 5A347)
Messages           : SMS, Email
Internet Browser :  HTML (Safari)
Games               : Yes
Colour               :  Black (8/16 GB), White (16 GB)
Camera              : 2 MP, 1600 × 1200 pixels
Standby Time      : up to 300 hours
Talk time           :  up to 10 hours
Other Features    : TV output Photo browser / editor, 
                           iPod audio / video player, 
                           integrated handsfree, 
                           Voice memo, 
                           A-GPS, 
                           built-in GPS receiver