I can't comment on the reliability of Amazons rebate program...but I did do
alot of research on that site before I bought my new phone.
Let me start from the begining. My goal was to upgrade my phone for free or
as little as possible. I was first attracted to AT&T wireless because they
have plans where you can get a free color screen phone if you sign up for 2
years. The plans were their standard plans, nothing special. I wanted a
better than average color phone so I went to Amazon to compare. Low and
behold even the coolest phones were free there! But I dug deeper. The AT&T
plans all seemed to have less minutes than the plans on AT&T's site. Also,
to qualify for the free phone from T-Mobile, you had to be in a plan for
39.99 or more. I pay 29.99 and didn't want to raise my rate.
I initailly settled on a Nokia 3595 from AT&T with a two year
contract...bottom line color phone but better than what I had. I called up
customer service at T-mobile to cancel my account and, as I expected, was
given a sales pitch to get me to stay. I ended up buying a Nokia 6610 for
$35 and got a free month of service...so the phone is pretty much free. I
only had to renew my existing service, which I am happy with, for one year
rather then take a chance on a service I didn't like for 2 years.
Bottom Line - Do your research before you go for one of the rebates. The
phone might be free but you may get locked into a plan that you don't like
for a long time!

Slow, but reliable.  My phone rebates from Amazon (done 2 so far) have
taken about 8 weeks after I mailed them.  However, with at least
T-Mobile  you have to include a couple of the bill so 8 weeks plus
however long it takes you to get your first bill.

My last one ended up being 2-1/2 months after I purchased the phone
(LOL).