I went from an Iphone 3G, to the Samsung Captivate (returned it before the 30 day period was up), went back to the 3G and waited for the Inspire to come out.
I really disliked the Captivate. The only positives I found were the beautiful screen and the Droid apps, etc (which obviously aren't specific to the phone). The phone's sharp edges make it uncomfortable to hold in your hand, and I found of the placement of the buttons (power, etc.) very awkward. It also could not get my email notifications down. The phone would tell me I had email, I would go check, and no email... Then when it did work, I would check my email, clear the notifications and 30 seconds later I would have another email notification and no new email in my inbox. I had to force closes on native apps all the time after an error message would pop up. Also, the thing refused to auto sync with my car's bluetooth hands free setup. I had to manually connect the phone each time I got into the car, or it wouldn't work at all. Another thing that was constant was a strange laggy touch screen. Each time I would try to drag my finger across the screen, it would hiccup and then have to catch itself up. My battery life was awful. Around dinner time, the phone was dinging at me to charge the phone or it would die. And that's barely using the phone. Pretty useless to me...
I realize you already have the phone, but someone else might be interested in the issues...
I love my Inspire. It's fast, no lag, touch screen is very responsive, haven't had to force close anything since I received the phone, and it's pretty intuitive to use. I will say that moving from an iphone 3Gs, it's close to the same size and shape (this is a little bigger), but the button placement is almost identical and it works well for me. The rounded edges and curved back make it comfortable to hold in your hand. I was worried that it didn't have the AMOLED screen, and wondered if that would be noticable coming from the Samsung, but it's not at all. The screen is gorgeous and huge. Battery life is so-so, but is about the same as my iphone was... By the end of the day, I'm at about 50% battery life (using it moderately, not surfing all day, etc). No complaints at all. So glad I returned the Captivate and waited for this!