Well, I have the device in Orange form...
The form factor is nice, although it's not the smallest ppc out there, the device is a tad bit slow at times, but overall is efficient. Obviously you've got your GPS on it as well, which I can't really judge as I've not tried it. The memory card is MiniSD, though there's been limited success though with 4GB versions. I couldn't comment on bundled software with HTC, but if you get the Orange version i.e. the M700 there's nothing special really, and you'd perhaps want to flash it with another ROM to free up some memory.
Overall, I'm pretty happy with mine, I've got the white version which looks really cool...but I've bought some good software for it, (Wisbar Advance, Pocketbreeze, SPB Shell & Time), and I do pretty much everything with it now, use it as a phone, mp3 player, PDA etc etc.
I'd say probably one of the best on the market at the moment bar the keyboard. Probably not the best looking compared to the P4350 or P3300, but you're compensating for pretty much half the processor power there.