I had no plans to update my iPhone 4 when I got it. However, when I saw how easy it was to jailbreak, and the latest verdict that jailbreaking is legal, I went ahead and jailbreak.
No problems here, and I still have iOS 4.0. It's a very empowering feeling, and I like having the ability to take advantage of both sides of the argument. It's not like I'm tied down to jailbreak; the more options, usually the better.
-C
Sent from my iPhone 4