I'm now on day 3 with the Audiovox PPC-6601 from Sprint. Overall, I think I made the right decision. The screen is very nice, and seems to be more clear and have better contrast than my Viewsonic V37. I think the keypad on the Treo 650 is better, but the slide-out keypad on the 6601 in exchange for more screen real estate is definitely a plus.
Exchange ActiveSync works like a champ, and I also have a POP3 account set up. It's so cool to be driving down the Interstate, receiving and reading new e-mails, all the while oblivious to other drivers honking and careening out of the way.
You definitely need a headset for making & taking calls. The phone is just a little too big to feel comfortable next to your face. I feel silly every time I make a call in a public place. Plus, there's the greasy smears and dusting of beard crust on the screen when I'm through. I suspect even if you've just scrubbed your face with Noxzema (which I apparently need), you're going to leave smears on the screen. The included stereo earbuds and microphone work very well. Man, I gotta start cleaning my ears, too.
Speaking of earbuds, I loaded up a few MP3s. It works, but the sound quality leaves a little to be desired.
I was disappointed that the battery only lasted 9 hours yesterday. Of course, I had used it quite a bit making calls, surfing the Internet, and letting my co-workers handle it. I definitely need to get another cradle for the house, or at least a charger. Unfortunately, I've had a hard time finding accessories.
My next goal is to try out the bluetooth support. From what I've read, it's possible to use the phone as a modem. May laptop doesn't have bluetooth, so I need to buy a USB adapter. I'd also like to try one of those bluetooth headsets.
The phone has locked up on me a few times, requiring a reset. That disturbs me. I'm also a little bummed out that it doesn't have a built-in camera. I guess you get what you pay for. Hey... wait a minute!
Update: Here's a picture.