The only aspect of the HTC Tattoo we have a problem with is the resistive screen. We understand the cost-saving implementation of it but from our experience with resistive screens (think WinMob phones), they simply pale in comparison to capacitive touchscreens (think all other Android phones, iPhone, Palm Pre). Capacitive screens in the mobile space just seem to do a better job in registering touch inputs. Remember, Android isn't built to use with styli, it's a finger-friendly capacitive environment.
Apparently, HTC thinks differently. After unveiling the HTC Tattoo, HTC trumpeted the company line, tweeting, "Capacitive screens at small sizes are hard to be accurate with. Resistive ends up registering fewer miss-clicks." HTC could be right but we'd be more forgiving if HTC admitted it was more a financial move than anything else.
Our biggest issue is that if HTC really wants to mass-market this phone and offer it to everyone worldwide, offering a potentially sub-par Android experience might dissuade people from future HTC Android purchases. Obviously, we're jumping the gun a bit--the resistive screen may still turn out to be a great option for the mass market--but we always felt resistive screens were technology of yore, not 2009.