I've never preordered any movies (well, I used to preorder Disney videos from Disney Store YEARS ago when they came with those beautiful lithograph prints, ah... the good ol' days). I just print off my $5 OFF Coupon from Disney Movie Rewards and go into Walmart (where they're usually $5 less the first week of release) and get my blurays for less than the DVD release!
That said, Amazons' preorder prices are usually great, I'd just rather have my new Disney releases the morning of, you know?