For comic book fans, a lot of the main plot was very true to the Wolverine Origin story. Sabretooth and Logan grew up together, became brothers and developed a great enmity between them due to Victor's bloodlust.
They fudge a few things, like instead of being in Alpha Flight, he teams up with William Stryker and his mutant-hunting team, but all in all as a comic loyalist I was willing to overlook obvious departures from the comic lore.
Only thing that bugged me was the trailer: it showed a lot of mutants in the commercial, so you get the sense that you'll be seeing a lot of Gambit, Emma Frost and a few others. They're barely in it: this is a strictly Wolverine/Sabretooth movie.