It is a very nice piece of hardware that packs in a very small form almost any feature of bigger-size, and higher-cost, models.
GPS, bluetooth, FM radio, acceleration sensors, camera, WiFi.
But the hardware is not so much relevant when the software does not use it properly.
The HTC Tattoo has been marketed with Android OS 1.6. The bluetooth profile does not provide support for file sharing and contact sharing. The WiFi does not provide support for various type of WPA2 enterprise network (e.g. Eduroam). Many Android market application require a 2.x version of Android, and for this reason Tattoo users will find less and less applications on the market as time passes.
All this issues, and many more it is easy to find on the dedicated forums, can be fixed by upgrading the HTC Tattoo to latest Android.
Some non-official upgrades have been developed by passionate modders and developers of custom ROMs. The 2.1 and 2.2 custom ROMs (see, e.g., http://forum.xda-developers.com/showthread.php?t=698576 ) are clear evidence the HTC Tattoo is able to work with a 2.x Android OS, providing a smooth and nice user experience (the only relatively relevant issues remaining to be fixed are getting the camera and radio to work).
Therefore we firmly ask to HTC to provide HTC Tattoo users with an official upgrade to a 2.x version of the Android OS.
This would enable Tattoo owners to enjoy their product at best, finally removing the feel of being the only HTC customers abandoned by HTC and excluded from getting the Android update they deserve (e.g. HTC Hero is an earlier product and it has been updated).