For one, I ordered my first package through Cellular One (now Cingular) in 2000. I did everything over the phone and was told I would have my phone in 2 days. Two weeks later, I'm driving to the UPS shipping warehouse because they can't seem to navigate a map.
You can only imagine the amount of time I wasted in those two weeks.
Second, I went through a period of about 6-8 months where my bill was erroneous EACH month. Again, you can only imagine the amount of time I wasted trying to get my account fixed.
Third, I've purchased 2 phones in the last 1.5 years that both had to be taken back because they were faulty. Is that Cingular's fault? Probably not as they were Motorola phones, but still. :shrug:
All-in-all, I wouldn't recommend them.