One of the main reasons I got enthralled by Deadly Premonition, besides the obvious ones such as my love for twin peaks, weirdness, alternate world horror and original zombies, is the way the game uses Zach.
I've seen some mixed opinions and interpretations of Zach here, but most people seem to merely focus on his place in the plot and backstory and whatnot. I feel that Zack is one of the best attempts at bridging the gap between the player and the player character. A trauma-induced second personality that the protagonist confides in, consults, and ultimately hides behind when exposed to new threatening situations is in my opinion one of the best solutions I have yet to see. Amongst other things it enables some smooth plot exposition and gives the reason why, in this case, agent York is merely watching from the back seat as it were, while someone else is at the wheel.
I would love to see, or create, more innovative approaches to this. I've always had a soft spot for a mental second, but it mostly ends up being an antagonist... Which isn't always bad, but not what I'm out for.
The place of the player, and the general narration is something many games stumble and fall over, and not much innovation is present. It would be great to see more inspirational examples, or hear general thoughts on this as well.

Ever play Omikron: The Nomad Soul (just The Nomad Soul in Europe)? 
 
In that game you are the player, yourself, the game breaks the 4th wall and literally tells you that it needs YOU to help, and your 'soul' gets transported into this world. It's always stuck with me even though the game wasn't that great (ok, it was great, but had some major playability issues) 
 
At least that's how I remember it, I havnt played it since it was new on the Dreamcast. 
 
EDIT: Heavy Rain fans may be interested to know that Nomad Soul was a Quantic Dream game. Their first in fact, and features music by David Bowie. They are apparently planning a sequel.

They are apparently planning a sequel. "

" Their first in fact, and features music by David Bowie. "

Not only music, but also Bowie himself. He cameod as two characters and had input into the game's story.

To be honest, I can't really find another example like Zach. That is weird - video game characters tend to be very self-referential, but the execution of the whole "I'm a duder in a video game" is pretty straight-forward. I really think Deadly Premonition contributes to the video game world with that type of narration. I hope someone rips it off from it.

Despite having played the game all the way through and fully understanding Zach's significance, I never once doubted that Zach was also the player. Really, whenever you're given a choice of doing something, that choice is somehow directed toward Zach. I thought that this was a really cool idea, although it would've been nice for them to do like Codemasters does in games like GRID by including voice audio for names and nicknames that players may potentially enter as their own. For some reason, a lot of people feel that there can only be one answer to everything, and that isn't the case with Zach.

I enjoy the way Zach was implemented into the game, but I don't think that is the best answer most of the time. When I look for an immersive character experience the some of the best examples I look at are Fallout 3 ,Bioshock, and Half-Life. I suppose what I'm trying to get at is that the best way to really put the player in the character's shoes is to create a situation in which the shared experience between character and player is equal and identical in all parts. You learn about the world at the same time the character is, and because of that the mental switch from functioning in reality to functioning with the game world is seamless. 
 
Obviously this doesn't work in all cases though. Sometimes game designers want to tell a specific story with a complex character who has already had a wealth of life experiences and functions according to his own set of principle. Now that's fine too, but at that point it becomes more of a playable movie than a game. The Metal Gear, Grand Theft Auto, and Final Fantasy franchises fall under this jurisdiction. Obviously these are games that still have complex narratives with a good level of emotional depth, but the farthest you are ever going to get is sympathizing with the character. 
 
Zach is a neat concept because he sits somewhere in between those two concrete methods of story telling in games, and although I don't think a character with a degraded mental state like York's will work in every game, I feel like that direct player to character interface is an exciting idea and I would like to see more games use it.

This isn't the first game to use that kind of concept actually. Both Baten Kaitos games feature you as a guardian spirit from another world, and the main characters will frequently turn directly to the screen and consult you for advice. Most of it doesn't really strongly affect the game, but it's still a nice touch. Everything you play is through the eyes of the spirit, which lets them mess with the perspective thing a little bit as well.

The whole Zach thing seemed stupid to me at first, but now it's getting kind of interesting, especially with the Origin Story. It's sort of like you are the 'imaginary friend' possessing the kid in The Shining, only you're normal and he's weird.