This is why I'm frustrated by the UX of iOS 4.0 running on my iPhone 3G. It is plagued with these unpredictable freezes, especially in Safari, which makes it unusable sometimes. We're talking total UI non-responsiveness for anywhere from 15-120 seconds, right smack in the middle of you're doing something. Very let down by them in this area. I've already learned of an unofficial way to downgrade back to 3.x, however, I've been reluctant to do it because I have some legacy contract projects who want me to support 4.0, so I need to keep something running it.
Other than this issue, though, Apple provides an awesome UX and has been a no-brainer choice over Microsoft -- a company I had also noticed many times in the past was copying the surface aspect of what a competitor did, often Apple, but not getting the fundamentals right, and making themselves look like idiots.