The 3.0 OS for the iphone came out on Wednesday, June 17th. I gave it a few days to make sure there were no major bugs that weren't discovered until mass install. Once everything looked good, I went for it!
There are a couple different ways to upgrade your firmware. You can either upgrade via itunes and go from there, or just download the firmware and restore from backup. I went this route, as a clean wipe of my phone seemed about due.
I did the full restore, which dumped me into a fresh iphone with nothing on it. My itunes then asked if i wanted to restore my content from a previous backup, to which i said yes. This gave me back SOME of the content I had before, but not much.
I then went and got the redsnow jalbreak package (you can download it here) and proceeded to jailbreak my new firmware. This succeeded without a hitch. Now, what about the new firmware itself?
The biggest improvements I have seen are the ability to cut, copy, and paste, and the landscape email. These two are things I have been wanting for some time, and Apple has apparently heard our pleas. Apparently, the multimedia messages will not work quite yet, but should sometime soon? I dont know about that, but we shall see. All in all, the new firmware seems smooth and responsive. There do not seem to be any drawbacks as of yet.