A lot of users have asked me to compare the Treo 700p with the 650, 700w and Audiovox 6700.  Recently the Motorola Q has been added into the mix, however, I have not yet had a chance to get my hands on one yet.  I'm going to throw these smartphones into two categories:  Palm and Windows Mobile.  I did a technical comparison of these phones a while back and that's great, but a technical grid does not show how one will use the device in real life.  While one device may have better specs on paper, once we get it into the field it may completely suck.  This review is moistly subjective based on my experiences with each device.  Your mileage may vary.

Windows Mobile devices:
The biggest problem with Windows Mobile devices is Windows Mobile 5 itself.  Anyone who knows me or reads my articles will know that I'm not a fan of either the Palm OS or Windows Mobile 5, but I would take Palm over anything else.  Windows Mobile's e-mail and web browsing are sub-par with notification screens for no reason yet important notifications are buried or go missed.  The GUI is slow and clunky.  The phone is not user oriented like the Palm's Treo line (simple on-screen answer button and whatnot).  The e-mail application needs to dial and disconnect EVDO every time it checks mail and I have yet to find any e-mail program on WM5 that does 1/2 of what ChatterEmail does.  I believe that someday Windows Mobile will take over Palm, but that day is not today.

PPC-6700 - My least favorite device is the PPC-6700.  While this device actually looks amazing on paper, in real life it just falls short.  The PPC-6700 has this nifty side sliding keyboard that I thought I would love.  Turns out that the keyboard takes away from the experience.  Rather than being able to one-hand the phone I am required to use two hands for simple things like e-mail and whatnot.  This is not an issue on the Treo line.  The battery life for what I was doing was very, very poor.  WiFi sounded great but in real life it was not much faster than EVDO.  The keyguard was iffy at best and I placed a number of calls that I did not intent to place while the phone was in my pocket.  I'm not sure if this was a failure of the 6700 or Windows Mobile 5.  The device as a whole feels too big and cumbersome in my hand, even though it's not that much larger than a Treo.  All in all I didn't like the 6700 at all.
Palm Treo 700w - The Treo 700w looks a lot worse than the PPC-6700 on paper as it has a slower processor, no WiFi and a bunch of other lower specs, but once I started using it I was much happier with my Windows Mobile experience.  This device has a great image based speed dial, the speed was nice and while the keyboard is always out and takes up a lot of room, it's very easy to type on even with one hand.  The biggest gripes I had here was the lack of integration of the 5-way navigation.  While some apps were aware and honored the navigation, others did not.  This made the interaction with the device different on a per-program basis and that ends up being annoying.
Palm devices:
I'm not a Palm fan either.  I think the Palm multitasking (if you can call it that) sucks, I can't get some great apps on the Palm such as SlingBox, LogMeIn and I have to pay for VPN access which comes free on WM5 devices.  I do believe it's the lesser of two evils, seems to behave better than WM5 and with the Treo line is able to integrate phone functionality much better than any other smartphone out there to date, Symbian phones included.

Palm Treo 650 - I used the Treo 650 for a long time.  My primary use is e-mail and phone with web being a distant third.  By using ChatterEmail I was able to get e-mail in real time to my phone without the use of a middleware server (eliminating monthly charges).  The biggest problem with the device is that it is a 1xRTT data connection on CDMA networks and when I have an open data connection I can not receive an incoming call.  The camera is mediocre at best and there's no WiFi, but the device is stable and works well as a phone and e-mail client.  I am able to access my network through third party VPN software, but that does cost more.  Oddly enough the included Documents To Go application works with Word, Excel and PowerPoint documents better than the software included in Windows Moble devices, which I find odd to say the least.  This device has hardly any on-board memory at all so a SD card is almost required.
Palm Treo 700p - This is my device of choice right now.  It's a good form factor, has EVDO so I can get an incoming phone call while in a data connection and the extra memory is nice, but not enough.  There's still no WiFi but I'm OK with that as long as my EVDO connection is fast enough.  I have noticed that the phone is a bit more flaky than the Treo 650, but not as bad as a Treo 700w or PPC-6700.  With ChatterEmail added I'm able to get push e-mail to my phone and not miss a single call.  The 1.2MP camera is nice, but it's still a cell-phone camera and if you're serious about taking pictures you'll want a real digital camera.  I was a bit disappointed that the images based speed dial from the Treo 700w was not included, but the added 'send SMS to caller' and 'Add Phone Number to Exsisting Contact' options are a nice addon.  Anyone one a Treo 600 should dump it now and move to a 700p.  Anyone on a 650 may want to examine how they use their phone and see if the upgrade is really required.  If you're a heavy data user, the 700p should be an easy sell.
I know these are just a few points boiled down.  Each phone has its plusses and minuses, but I would say that in my world the 700p is the hands down winner.  If you're really liking the idea of WM5 or if you're a MS zealot that refuses to use Palm then I would stay with the Treo 700w as opposed to the PPC-6700 as it's just a better designed device.  Everyone uses their phone differently, and some may disagree with what I have said.  What are your thoughts on each phone?  If you could pick any device and it was free, which would you pick?