As you know, I received the Sony Ericsson P800 last week. I put it up on eBay yesterday. Let me explain. The P800 is, by far, the greatest melding of mobile phone and PDA functionality ever, but there were a few subtle problems with it that I just couldn't stand. The first and most important was the vibrate feature. It just wasn't strong enough (because of the size of the device) and so I often missed calls (I ALWAYS have vibrate on and so should you :P). Speaking of its size, it isn't large by any stretch, especially when you consider all that it has (200MHz processor, Symbian OS, 208x320 12-bit screen, digital camera, Bluetooth, IR, etc.), but the fact is, I've become so used to devices that are three-quarters of an inch thick and weigh less than three ounces that I just can't bring myself to use something much larger, regardless of its features. One other thing that really got on my nerves is that when you used the phone without the flip (you have the option of using the flip-keypad or not), there is no easy way to go into speakerphone mode. You have to pull out the stylus and 'click' to it (with the flip you just flip it open and it turns on the speakerphone). There were a few other things that really got under my skin and I'm assuming they'll fix all of them with the next software update, but that isn't going to help its weight or form-factor.
A couple of days ago I ordered the Nokia 7250 and received it this morning. It's very similar to the Nokia 7210 that I had just before I got the P800 last week. The only real difference is that the 7250 has a built-in camera and much more memory.
I'm waiting on the Sony Ericsson T610 (more info here), which should be available in Europe within the next two months. This is the upgrade to the T68i that I had last year. This is the phone to end all phones.