I've had my Pre for about 2 weeks (on unit #2) and I think I'm gonna stick with it. At first I wasn't sure, so I kept my Treo 755p just in case.
Well today I started gathering all-things Treo to put together my ebay/CL package.I fired up the Treo (probably for the last time

) and noticed how much I have grown accustomed to things...things I will sorely miss and know will never see on the Pre.
1) The rocker - Being able to navigate with one hand is priceless. And knowing when you select something (middle button), it's going to be selected.
2) The keyboard - Considering it's size and crampness, the Pre's keyboard is pretty decent. But I used to be able to haul freakin a** on my Treo's keyboard. I mean it got to the point where I wasn't even looking anymore..haha...The big buttons and spacing were perfect!
3) Expandable storage - For obvious reasons. I know WebOS is supposed to revolutionize how we treat our phones; not so much a storage device, but a device that can easily grab our content stored on the web seamlessly...I'd still like to have that option to store more than 8gb on my device.