My first BB was an 8700 a little more than a year ago. I used it for about five months before it finally succumbed to the effects of water damage that I inflicted upon it. I loved that thing and hated the idea of using anything other than a BB. I felt like it was huge, though -- which is funny because when I first played with it I thought it wouldn't be wide enough -- so I decided to use a 7130c. That still felt like a brick to me, so I contemplated getting a Pearl, but when the early reviews of the Curve hit, I decided to wait and see. By the time it launched, I was sold on it.
I went to a store and held it in my hand. That was all I needed. I went home, ordered it with my upgrade, got it on Tuesday and sold my 7130c on Wednesday.
I love this device. Coming from an 8700 you'll have to adjust to using the trackball and BB logo menu button to do what the scroll wheel does on the 8700. And the Curve is not quite as wide and the buttons are a bit smaller. That's not subjective, that's fact, and depending on your hand size you may find it more difficult to type on or, like me, just adapt pretty easily. I won't lie, I misfire sometimes on this keyboard, but I've had it four days. It'll take a little time to adjust but not too much. The keyboard is really nice, IMO, as the keys are stiff and provide excellent tactile response. I really enjoy typing on it and it's actually very easy to type one handed on, something I found difficult to do on the 8700, which I would say has to do with the width of the Curve.
I have played with the 8800 repeatedly. There are three reasons I didn't purchase one based on my own preferences: no camera, too wide and the keyboard is mushy with no space between the keys.
Going from the 7130 to the Curve ... it was a huge upgrade for me. I particularly think RIM has come a long way in the past year in the OS and that's evident on the Curve.
I love mine. Did I already mention that? I have repeatedly thought to myself that the Curve is the phone I wanted when I first bought the 8700.
With my Bold, I'm just an e-mail away.