The HTC HD2, manufactured by HTC, is the first smartphone with a 4.3 inches touchscreen, and the first Windows Mobile phone with capacitive multi-touch capabilities.
Released with Windows Mobile 6.5 in September 2009, it's a long-lasting smartphone on the market, due to the large amounts of modded ROM and Operating Systems made available by third part developers for it.
Actually are available many Windows Mobile versions (6.5, 6.5.3, 6.5.5), Windows Phone 7 (albeit illegally - Microsoft rejected HD2 hardware due to not compliant with the three button chassis guideline) and, thanks to the work of developers, Android Froyo and Gingerbread, Ubuntu, Windows 95, 98 and XP.
It is today the most supported device ever, and still on the edge after two years from its release date.
I personally had installed the WM stock ROM from HTC, switching soon to WM 6.5.5 using cooked ROM Artemis (I tried Energy too, but was less stable). Then I had for about one month a dual boot with Android on SD card (AmericanDroid). It was far more usable than WM, and apps were more, so I soon decided to go for Android on NAND, removing definitively the dead-man-walking WM.
I tried TyphooN, MIUI stock, CoreDroid and HyperDroid. I've a preference for CyanogenMod, so MIUI was soon dropped. CoreDroid and HyperDroid were less stable (and more battery hungry) then TyphooN, so actually my HD2 runs a TyphooN CyanogenMod 7 Nightly 3.3.5.
I don't update frequently my ROM (there's 3.4.1 out), unless there's a reason to do that (new functionalities, O.S. version update, critical bug fix). The update process is painless and simple, and I usually do from the HD2 without using a PC connection through ClockWorkMod.
05/07/2011 Mango has been ported too on the HD2.
CPU Processing Speed
1GHz Snapdragon™ processor
Power & Battery
Battery type: Rechargeable Lithium-ion battery
Capacity: 1230 mAh
Camera
5 megapixel color camera
Auto focus
Dual LED flashlight
Connectors
3.5 mm stereo audio jack
Standard Micro-USB (5-pin micro-USB 2.0)
Sensors
G-Sensor
Proximity sensor
Ambient light sensor
Display
Type: Capacitive touch screen
Resolution: 480 X 800 WVGA
Storage
ROM: 512 MB
RAM: 448 MB
Expansion slot: microSD™ memory card (SD 2.0 compatible)
Europe: Network Bands
HSPA/WCDMA: 900/2100 MHz
GSM: 850/900/1800/1900 MHz
Internet
3G: Up to 7.2 Mbps download speed
3G: Up to 2 Mbps upload speed
GPRS: Up to 114 kbps download speed
EDGE: Up to 560 kbps download speed
Wi-Fi®: IEEE 802.11 b/g
Tethering
Internet Sharing through USB or Bluetooth
Wi-Fi Router
Bluetooth
Bluetooth® 2.1 with Enhanced Data Rate
Supported profiles: A2DP, AVRCP, BIP, BPP, DUN, FTP, GAP, GOEP, HFP, HID, HSP, OPP, PAN, PBAP, SAP, SPP