Give it at least 2 weeks.
When I left my Bold, the first week I contemplated several times getting another Bold. But I held out. Honestly - I think most people resist change, which sounds awkward considering the fact that most of us around here at some point or another, probably changed phones more times than we've changed underwear (well I hope not), haha
But the iPhone is getting there. 4.0 adds a lot of many needed features. After digging through the SDK and APIs and having 4.0 for almost 2 full days, there's a lot devs can do they never had the ability to do before.
Honestly - this time around, Apple has given devs the tools to utilize a lot of core functions, you may be surprised at what you see. Some people say 4.0 was too little too late or that it wasn't a WOW factor, but I don't think people will realize how big it is until they see how it can be implemented. I've been trying to weed through APIs for 2 whole days now and have only scratched the surface. Apple has given some amazing new tools and abilities to devs, which is huge for them. They are slowly moving away from that proprietary model.
As far as BB, it does what it's made to do well, but if you want multimedia and anything past that, BB isn't the right phone. I think RIM could do well with a little more innovation. But business is what they do best. I just wish they'd worry about their software and slow down on churning out the hardware. I think that's where they are lacking right now.