Installed Mint 10 amd64 RC this morning--nice!
No problems whatsoever, absolutely none--much impressed. Installed the codecs via the Welcome screen and then the DVD packages (immediately removed F-Spot right after but that's a personal preference). Copied over my settings that I backed up from Mint 9 32 bit (old machine) and I was ready to go. So far it's been completely stable and very, very fast. And an excellent job of taking that rather dumbed down Ubuntu 10.10 (IMO) and Mint-a-fying it.
It came at the right time as I recently (and finally) updated from a 7 year old PC to modern quad core and Mint 9 x86 with the PAE kernel and Mint 9 amd64 were having all sorts of audio problems and various quirks with the new machine. It was quite disheartening. Then I checked DistroWatch and saw that "Julia" was out and immediately downloaded and installed the amd64 version. No more problems.
This has to be Mint's best effort so far.
"Humph. Choice, it is the quintessential Linux delusion, simultaneously the source of it's greatest strength, and it's greatest weakness." (All apologies to The Architect)