Across the board professionals are reviewing Batman: Arkham Asylum and praising it's pacing, story, memorable moments, varied combat, and extras. Sure does make me wish I had the cash to go and score one of the numerous deals available right now (some stores selling the game as low as $40).
I'm sure I'll be able to pick up Batman later this holiday season as some of the bigger titles are launching, but I thought one reviews comment in particular was of note. Game Informer called Batman: Arkham Asylum "this year's Bioshock." That is some extremely high praise for a Batman game.