[Galaxy Note II Q&A, Help & Troubleshooting] Cloudane:
As a techie who knows he's unlikely to end up bricking it (and accepts that if I do it's probably my fault for doing something stupid) I'll not be intimidated by Samsung not to root, just like I wasn't intimidated by HTC, and I'm sure it's probably not me (but rather, non-techies) who they're trying to intimidate.

Besides, from what I was reading you just have to put it back to stock to get your warranty back. But even if a fault developed that bricked it (and not of my own doing, but I'd never overclock or anything anyway and am unlikely to do anything stupid), as I'm in the UK and we have a lot of consumer rights, I'd just keep parroting the Sale of Goods Act at them and possibly threatening a small claims court until they got the message :p

It's like rooting any other Android phone: naturally they won't help you with it, and I can see where they're coming from in that they won't do warranty returns if a non-technical person tries it and screws it up and then claims that it's faulty. That's what they mean - not genuine hardware faults, but being asked to cover a bad flash. So basically: only do it if you're confident, and it's at your own risk if you don't have a clue what you're doing. But it's quite difficult (if not impossible?) to permanently brick to the point where you can't even get to ODIN download mode, it's just that a lot of people think "won't boot into a working OS" means "bricked" and throw the towel in. (Personally I think it's difficult to even "brick" the OS as long as you take your time and read the instructions properly). That's where you can get unstuck as there's nothing actually wrong with the phone's hardware you just don't know what you're doing and that's where they're within their rights to say "no" to helping you out with a free unbricking or replacement. Even within consumer laws.

There's less reason to be put off than with a HTC phone, as the bootloader isn't locked so you don't have to go through the tedium of a full wipe and having to download all your apps again.

I do find that people who develop tools and tutorials tend to overcomplicate it with paragraphs of instructions and complex UIs full of a billion functions and tabs. Here's how I do it in Arch Linux:

Install Heimdall.https://aur.archlinux.org/packages/heimdall/

Get CWM Recovery: http://www.clockworkmod.com/rommanager

Download the touch version for Samsung Galaxy Note 2 (HSPA+)

Get CWM-SuperSU: http://xdaforums.com/showthread.php?t=1538053

Copy it to the SD storage.

To copy to SD storage if MTP isn't working in Arch:

sudo pacman -S libmtp
mtp-detect
mtp-connect
mtp-sendfile UPDATE-SuperSU-vx.xx.zip UPDATE-SuperSU-vx.xx.zip

Plug phone into PC

Turn it off

Hold down Volume DOWN, home and power until download mode screen appears. Press volume up to accept flash mode warning.

sudo heimdall flash --no-reboot --recovery recovery-clockwork-touch-x.x.x.x-n7100.bin

This should work, if not try a different USB port, try re-entering download mode etc.

While still at the download mode screen (if you reboot completely it'll re-flash recovery to stock) hold Volume UP, home and power until the Samsung logo repeats itself then let go, eventually CWM Recovery will appear.

Install zip from SD card

Select the CWM SuperSU zip

Reboot

That's it!

Nothing more complicated than that. In Windows you just basically use ODIN to do the same thing, but this is one of those occasions where things are actually easier to do in Linux than Windows.

Edit: Obviously you follow the above at your own risk and should learn how everything works - I'm just sharing my own notes to show how easy it can be.