Well, I travel a lot and often find myself in a hotel room or at a conference where I and one or two fellow employees need a quick conference call to the boss or someone at the office. This lets me quickly set up and make the call with all of us near the phone. Some phones have speakerphones that work real well and most don't. The old Siemens SX-56 had a really good speakerphone for this purpose. The LG4500 also has a good speakerphone. As to the screen resolution, the 320x240 provides extra sharpness to the characters and also allows for more text on the screen. I too need reading glasses or longer (much longer) arms so sharper characters and more of them makes reading easier (less scrolling).
BT 1.2 makes a very big difference in the sound quality on a BT headset. Crackling, popping and other noises seem to dissapear. The serial port profile will allow transfer of the address book to a BT hands free in car BT set up. Without it you have to dial from the phone which kind of defeats the point. No word about Voice Dialing but that is one feature I would really really like to see. I keep hoping.

Finally, slimmer means it doesn't catch on everything you walk by or getting in and out of your car (maybe you don't have this problem). The less it sticks out from my hip the better I will like it.