I have been using the Z500 for about 3 weeks now. Like most things, it has its pros and cons. First the cons:
The camera stinks. Don't plan on taking any family photos with it. The screen is CSTN and not TFT so it washes out easily in sunlight. There are not many ringtones or graphics included with the phone. Battery is only avg. SE claims something like 10 hrs talk time. I want some of what they are smoking. Expect around 4 hrs.
Now the pros:
The address book is terrific. A lot of thought went into it. The build quality is first rate, a very solid feeling phone. Unlike my other phones, (Nokia, SE, Samsung) I have yet to drop a call! The speakerphone us usefull too.
Overall I am very pleased. It makes the calls I need it to and keeps track of my contacts and it is worth the $149 I paid. One interesting thing though, with Cingular, the SIM card only holds 250 contacts while the phone holds 510. I currently have 420 in the phone. Cingular says that they have a new high capacity SIM coming, but it will be 2 or 3 months.