The update process is ridiculously complex, especially since many handhelds now support reliable Firmware-Over-The-Air (FOTA) style updates but it worked pretty well for me and seems reasonable robust. I was forced to abort the update mid way on my first attempt and was pleasantly surprised not to have bricked the phone, I was able to restart and start over without any problems. The update adds all of the Windows Mobile 6 improvements and flaws the device now has "native" Microsoft office app viewers, Mobile IE is marginally better but still seriously limited, the Samsung UI themes seem to be better but I need to try them out in ager to be certain, the Samsung\AT&T crippled JAVA VM is still crippled (you are forced to confirm net access for each application every time you ask it to run _and_ every time that app tries to access the net), Internet Connection Sharing is still available and still hidden from the standard user interface so you need to set up a shortcut in your Start Menu to make it easily available. Internet Connection Sharing over Bluetooth with Vista (on a Dell XPS M1330) still doesn't work as the problem there appears to be Microsoft's failure to support the Bluetooth PAN profile on Vista. One excellent piece of news is that Google Maps Mobile's cellular location awareness mechanism works - this did not work on the WM5 firmware and had been a significant disappointment for (some) Blackjack owners.
The update _requires_ Windows 2000 or Windows XP so if you don't have a PC running one of those then you will need to borrow a friends or use Virtual Box to set up a temporary Virtual PC that supports USB pass through. The latter is vital - the update uses four different USB communication modes and drivers so a Virtual Machine Manager that doesn't support USB pass through (like Virtual PC 2007) is not going to be any use.