Note: These comments are for people who have seen the movie.
Vanilla Sky is a brilliant, complex, and thrilling movie that existentially explores exactly what the tag-line says: LoveHateDreamsLifeWorkPlayFriends. Maybe the movie plot can come into focus for confused movie-goers if one looks at it from a different angle.
Considering the following:
Now, I have not painstakingly gone through the film scene by scene, so I will have to further examine my assertions, (and I welcome your thoughts) but give this a try and see if the movie doesn't fall into place: Where exactly does the debatable 'splice' occur?
Now, I'm not talking about the splice as it is explained by the L.E. 'technician', since that sequence itself could be actually interpreted as a rationalization inside of David Aames's mind/dream/coma state, but the true splice between reality and dream.
It seems to me that the reality of the car crash, the way that it is filmed (no explosion, for example) is a likely 'splice' point, and that any particular sequence containing an existential/dream/coma/non-reality feel to it -- whether it's shown onscreen before or after the crash -- is actually a part of Aames' personal journey toward self-realization inside of his own mind.
In that respect, then, we are left with two questions at the very end(if you know of more, let me know): is Aames actually disfigured, and where does he wake up?
If you don't get entirely wrapped up in the exact sequence of details in the plot, or at what particular point his dreams are scattered throughout, this movie becomes a fascinating exploration of a human on a journey to find himself and what that means in today's pop-culture society.

When I go out to the video store to rent a flick I usually trust IMDb's views on a film and, until this one, had never seen a flick rated 7.0 or above on the site I did not enjoy.
Sidney Lumet, a legendary director of some of the best films of the 20th century, really misstepped here by making one of the biggest mistakes a filmmaker can: filling a film's cast with thoroughly unlikeable characters with no real redeeming qualities whatsoever.
I like films with flawed characters, but no matter how dark someone's personality is we all have a bit of light in there too, we're all shades of gray with some darker or brighter than others. Mr. Lumet crossed this line by filling this movie with totally unsympathetic and almost masochistic pitch-black characters.
Ethan Hawke's Hank is a 30-something whining, immature, irresponsible man-child divorced from a marriage with a wife that hates him and a daughter who thinks he's a loser, which he very much is. His indecisiveness and willingness to let others do the dirty work for him because he's too cowardly to do it himself leads directly to their bank robbery plan falling apart and mother getting killed. By the time he stands up to his older brother at the end of the film, it's more pathetic than uplifting. Ethan Hawke plays his character well, but isn't given much to work with as he is portrayed as someone with a boot perpetually stamped on their face and he doesn't' particularly care that it's there.
Speaking of which his character's wife is equally as bad. Just about every single shot of the film she's in is her verbally berating him for rent and child support money and further grinding in his already non-existent self-esteem with insults. Seriously, that's just about all the character does. Her harpy-like behavior borders on malevolent.
Albert Finney plays their father Charles, and while Mr. Finney has been a great actor for many decades, he spends about 90% of this film with the same mouth open half-grimace on his face like he's suffering from the world's worst bout of constipation. For someone who's been an actor as long as Mr. Finney, you think he'd be more apt at emoting. Even though he doesn't show it much, his character is supposedly grief stricken and anger-filled. And when he smothers Andy at the film's conclusion it's akin to Dr. Frankenstein putting the monster he helped create out of it's own misery.
Marisa Tomei isn't given much to do with her character. Stuck in an unhappy marriage with Andy and having an affair with his brother for some unfathomable reason. When Andy's world begins to spiral out of control she logically jumps ship, but it really doesn't make her any less selfish or self-serving than any other character in the film, but probably the one with the most common sense at least.
And finally we come to Andy, played by the always good Philip Seymour Hoffman, is the only reason I rated this film a 3 instead of a 1. His performance of the heroin-addicted, embezzling financial executive who's "perfect crime" of robbing his parent's insured jewelry store goes awry is mesmerizing. His descent from calm master planner of a flawed scheme to unstable, deranged homicidal maniac is believable and tragic. Hoffman's character ends up being the film's chief villain, but it's hard to root against him given the alternatives are an emotionally castrated little brother and a father who's self-admitted poor early parenting led to his son's eventual psychosis and indirect, unintentional murder of his mother.
Ultimately this film is really only worth watching for PSH's great performance and it's family train wreck nature. Just don't expect there to be any characters worth cheering for, because there really aren't.