I'm a BB 8900 Curve user just now transitioning to the Captivate.
I'm on the unlimited data - grandfathered and I'd like to use tethering so I'm happy with that. I use Google Voice for texting so I dropped my texting plan and I'm super happy to just have data.
The keyboard on the Captivate is better than iPhone (my wife has an iPhone so I've used that a lot). I really like SwiftKeys as my keyboard - you just have to get used to typing and looking at the three suggested words (and clicking them) as you type - if you do, you will type pretty fast. I also like swype, but its predictive words aren't as good as SwitftKeys and I don't like going back and editing. The worst thing about the Captivate keyboard is editing what you've typed - I have a hard time getting the cursor where I want it. Android really needs a magnifying glass type mechanism like iPhone.
Email sucks - not even close compared to BB. But, there are so many other features and apps I like, that I'm willing to compromise a bit. I do hope that 2.2 gives some improvements. I hate the native Samsung email app - it is super slow, hesitates a lot on simple things, and doesn't render HTML very well. Touchdown shows great HTML and is very powerful, but I hate the look. K-9 is a bit in between.
Battery life has been sucking for me the last few days - not sure what it is. The Battery Usage says 70% screen so it doesn't appear to be a battery hog app - but I need to chase it down.
Browser is fantastic. And I really like the NewsRoom RSS app - it isn't as quick/efficient as Viiigo on the BB, but the pages are so much easier to read/access. The screen on this device is amazing - super clear - my middle age eyes like it way better than my BB 8900. That alone is motivation for sacrificing hard keys.
Volume of the phone isn't as good as I'd like - on everything. Even the music player doesn't max out very loud.
Phone is great - my BB was problematic after upgrading to 5.0...and the AT&T signal being marginal. The noise cancellation on the Samsung works great.
I like the way contacts sync/connect across apps. Nice to see the latest social media posts on the contact screen.
So far, if I can solve the battery issue, I'm happy. I think the froyo update will offer some big improvements and I think android has much greater potential than BB - other than messaging/email. But, I'm willing to sacrifice that...or wait till it gets better on android. And it is certainly cheaper than paying for BES.