I have about 5 of these NG appliances in service. Being at a remote office, I always apply the latest here and after testing, deploy at our other locations around the world.
Version 8.0.1 was scary. In fact with so many issues, I would suggest waiting until at least 8.0.2 comes out as some of these are DHCP-related. But the steps were rather straightforward if you have a reliable USB drive between 2GB and 32GB.
1> Download the following 3 items:
a. "Barracuda Firewall Install 8.0.1" utility. The current file name as I'm writing this is NGInstall_8.0.1-29.exe
b. The ISO of the firmware you want to install.
c. The PAR file from your current config unless you want to reconfigure from scratch. From the Firewall Admin utility, go to Configuration, Configuration Tree, right-click on Box and "Create PAR file..."
2> Using the NGinstall utility, do the following:
a. Insert your USB stick which will be reformatted.
b. Choose Auto Installation USB Flash Drive, next.
c. Under "Installation-script files", change the "Save to" to be your USB stick. Click Next
d. Under USB Flash Drive Settings:
1> Check the box for "Format USB flash drive"
2> Click the Import button next to "Image", then "Copy ISO Image". Select your firmware ISO for your appliance.
3> Click on the Modify box next to "PAR Files", click Import, then select your PAR file that you saved in step 1c, then select Close after the PAR file shows in the box.
4> Click Next.
e. Click Finish and let the utility build your bootable flash drive
(I also created a second USB stick with the 7.2.4 firmware in case I needed to roll back, which I would recommend doing)
3> Take that USB stick and put it into the appliance to upgrade.
4> Power the unit off, then back on.
5> Let it do the upgrade - do not interrupt it ! It will say "System Down" a couple of times, so don't get excited. It takes about 10 minutes and will beep a few times when complete. I waited an extra minute after the 3 beeps and the display said "System Down".
6> After you have heard the 3 beeps and waited a minute, power the unit off and remove the USB drive.
7> Boot the unit back up. It may restart after loading your config, so just let it do its thing.
Doing those steps had my site back up and online within about 10 minutes. But again, there are so many issues with this firmware version that I would consider it more of a public beta than a production release. I would strongly recommend waiting another release or two before considering the upgrade.