I've been using my 15-inch rMBP with Samsung (LSN) display. Mine was built to order two weeks ago (upgraded memory and processor). No issues here, amazing display, remarkable performance (upgrading from an iMac 27-inch Late 2009).
Like the OP, I was quite nervous after reading many threads of people paying upwards for $2500 for an inferior computer, however I am very satisfied with my purchase.
Don't forget to pickup AppleCare to extend your warranty!
Edit: Just noticed your from NZ. I've heard that most of the rMBPs shipped in Asia Pac are using Samsung displays.