Since you have used an iPhone 3G before, you may be familiar with the fast download speed on a 3G smartphone. If you are going to choose the Curve 8900 bear in mind that it is 2G only. So the download speed is much slower than the iPhone 3G.
The successor to the Bold 9000 is Onyx 9020 which will be released some time between September and November. If you prefer a touchscreen model. The Storm 2 is expected to be out in September.
I currently have the iphone 3g and i do not want to upgrade to the 3GS i want a good blackberry and been thinking about the curve8900 but are they comeing out with a new bold 2 or what else is a good blackberry?