SSH works fine for logging in to remote PCs using IPv6 addresses, but when you try to copy files with scp, it doesn't work. You are rewarded with the unhelpful message:
ssh: fe80: Name or service not known lost connection
Now what?
scp requires some strange syntax that you have to get just right, as this example shows:
$ scp filename carla@\[fe80::203:6dff:fe00:83cf%eth0\]:The IPv6 address must be enclosed in brackets, which must then be escaped. If you're logging in as a different user, the username goes outside the braces. And you must specify the local interface with the percent sign for Link Local addresses, just like with OpenSSH.
As this was written, neither the scp nor the OpenSSH manpages described the special IPv6 syntax, so you read it here first.