Well, that was painless, for the most part. I went to stand in line at the Valley Fair Apple store at 5:30 AM and I had an iPhone 3GS in my hands by 6:15 AM this morning. I didn't actually leave the building with it until 6:45, though, thanks to AT&T. Recall that I had swapped the SIM card with Scarlet's phone so she could enjoy the 3G this week. I had to momentarily undo that for the purpose of the 3GS acquisition, however, because officially my phone number wasn't due for a free upgrade yet. So officially Scarlet's number got the 3GS upgrade, and then we swapped SIM cards back again. Cumbersome, but in the end it was successful.
The compass reminds me a little bit of a compass you might use on the deck of a ship - it's a little bit unstable and while it usually points generally in the right direction, it jumps around a little. It also has this tendency to require you to "recalibrate it" by moving the phone in a figure 8 motion. Whenever I hold the phone out and do this, Scarlet giggles a little. She says it reminds her of something you'd see a snake charming swami do.
When I got to work, I paired the phone with my A2DP capable bluetooth headset. That seems to have been a totally painless exercise. I can now listen to Sirius/XM with the phone while not having to leave the browser on the computer pointing to the XM streaming server. The audio quality of the XM streams is quite nice, even when you get it over 3G. The downside is that, since it's a 3rd party app, it can't stream the audio in the background under other apps, like the built-in iPod app can. Maybe this is something Apple can loosen up with further API modifications later.
The only downside there is that I have to switch back and forth between the iPhone and the hockey-puck audio transmitter connected to the audio out on my work machine. I might wind up just choosing to use the wired headphones for the phone and the BT set for the computer like it was before.
The other downside now is that I have an inactive iPhone 2G now to get rid of. I suspect eBay will be saturated with them, and now that the 3G is being sold for $99, their value has plummeted. I also have a small collection of iPhone 2G cases that we no longer have any use for.