renhui, I have a iPaq 6945 (as well as a 6515). It has to be the BEST PPC Phone on the US market, to date. Sorry, TyTN fans, but it's not bing sold natively here and the battle between the 6945 and the TyTN come out with the 6945 slightly ahead:
6945 = Built-in, super sensitive GPS on TOP of BT & "B" WiFi.
TyTN = No GPS READ = NO GPS! Has "G" WiFi & BT.
6945 = Best keyboard. (Check reviews. People have raved about the flat, spacious STATIC, ALWAYS THERE keyboard). Easy, fast one-hand typing. Fast and easy dialing of numbers from the STATIC, ALWAYS THERE keyboard. Great backlit keys.
TyTN = slide out keyboard making typing on the fly one step further away AND having to wait that split second for the screen to reorientate itself to landscape. No one-hand typing (try balancing that thing with one hand, not gonna happen, sorry). Thickness and bulk are greatly affected because if the slide out keyboard while the 6945 stays thin. Poorly backlit keyboard compared to the 6945.
6945 = Faster processor (416MHz).
TyTN = Slightly slower processor (400MHz).
Trust me, every MHz counts on these things...
6945 = 1.3MP rear mounted cam.
TyTN = 2.0 MP rear mounted cam + VGA front mounted cam that no US provider or service can take advantage of. Sorry, no Skype video conferencing for you. Sorry no current cellular video conferencing for you. It's a useless addition on US shores (overseas it would be a different story in some Euro places). Wasted front cam... Not that VGA would have done much for you anyway...
6945 = EDGE.
TyTN = EDGE + HSDPA but no US GSM carrier has fully rolled out HSDPA. Cingular has incredibly few and incredibly sketchy HSDPA so, again, the TyTN comes up with current useless frills that mean little to nothing stateside at present. It will be about another year before Cingular gets a decent roll out of HSPDA. By then we'll be all on to the next new hot device and you just spent $900 on a phone that has feature that are literally USELESS for a huge chunck of time, sadly.
When you take everything into account, again, the 6945 comes out ahead. If you want a slamming device that you can use NOW and not have to wait months (possibily a year) to fully utilize, and want/need GPS you can't go wrong with the 6945.
Don't get me wrong, the TyTN is a very nice device, it just simply doesn't stack up right now against the 6945 since the front cam is basically useless (can't video conference) and HSDPA is barely deployed.
NOTE: Cingular has already pulled other HSDPA phones off their shelves at least once because they had some really pissed off customers buying the devices for HSDPA and Cingular didn't even have any HSDPA at the time... Until recently when very sketchy and very few metro areas recently went live and I hear the speeds in those few blessed pockets of HSDPA are disappointing to say the least... HSDPA, currently, is simply not fully deployed and not up to task yet.
But be your own judge. If you get a chance try to test both devices and choose for yourself.
If anyone has an questions about the iPaq 6945 (6900 series), feel free to ask me.
BTW, this whole entire post was typed quickly and painlessly, on the fly, on my 6945's keyboard.
tequila & cognac 
+ DC800 Trans/Receiver 
