Ok I was one of those people to buy the iPhone off of eBay cuase I just had to have it so I paid the price and got it. One of the best things I've ever done! Now saying that I don't have ATT so I had to unlock mine to make it work with T-Moblie.
After I unlocked it I added all those third partty apps such as iAno and well tons of stuff and it is awesome!
The phone its self works great the sound is great, the ease of use its really simple to get used to.
Texting on it or SMS as they call em works really well its like AIM if you will the MSGs are right on top of eachother really easy to use, But you cant send picture MSGs you have to eMail your pics which works if you have the internet set up with your iPhone if not then it can be frustrating.
eMail works very nicely on the iPhone I have Gmail which the iPhone supports.
The camera takes really good pictures but you can't zoom in on them unless you add a third party app.. It has google maps that come in handy alot its like having gps almost. It also has youtube on so you can watch any of you fave youtube vids! And I almost forgot Its an iPod music, videos, pics it does it all!
And one more thing I had a problem the screen with my first iPhone it was something called screen bubbles, so called apple to see if there was anything they could do guess what even though they knew I was not with ATT they said they would just give me a new iPhone! So in 3 days I had my new iPhone..:)
P.S if something like that happens to you and you unlocked your iPhone you HAVE to lock it back before you send it to them or they can charge you $150 dollars. Its in the fine print I always read the fine print..;)