It's amazing how much films have changed over the years and it seems we don't look upon our present films quite as fondly as we do with those of yesteryear. 
Even so, it seems many of these beloved "vintage" pictures are destined to erode away with time, simply because of the expense involved in restoring the film prints back into a worthy state.  Thank God Alfred Hitchcock made so many pictures loved by millions around the world. 
North By Northwest is one of the latest Hitch films to undergo a full restoration. 
As cinema was loosing it's stronghold on audiences to that squarish box called a TV, new and improved filmatic processes were being developed to lure people back to the cinemas.  
Once such concoction was "Vistavision".  the Vistavista process takes a 35mm camera negitve and runs it horizontally, as opposed to 35mm vertical.  In doing so the imprinted image is twice the physical size, so the end result is much improved picture resolution.  Hitchcock used this film stock for a few other films he shot in the 50's most notably Vertigo, and his own remake of the Man Who Knew too Much.

As is the case with many of Hitch's films, the less you know going in the better off you are.

Buuut without giving too much away Advertising Executive Roger Thornhill (Cary Grant in his 4th screen outting with Hitch) is mistaken for a secret government agent, one George Kaplan,(who happens to be tailing an espionage ring headed by a crimal mastermind known as Vandermann)  Roger is taken against his will by two heavies to an Estate owned by Lester Townsend (James Mason).  In an attempt to kill "Kaplan" one of the heavies, Leonard (A very young Martin Landau) forcefully poors and entire bottle of bourban down his throat, puts him behind the wheel of a car and pushes the car along a winding road with the intent of it going over the cliff.   However Roger manages to steer the car clear of the embankment, even in his drunken stupor and escapes. 
Before you know it, not only is Vandermann and his goons after Roger, but Roger becomes frontpage news with it appearing as though he has murdered Lester Townsend, who just so happens to by a United Nations official. 

Roger boards the Twentieth Century Express train which is heading for New York, and onboard he mets the lovely Eve Kendell (Eva Marie Saint).  Even though see knows he is wanted for murder, she none the less helps him out as she believes his innocence..........

VIDEO
If you thought Vertigo Looked Good, you ain't seen nothin' yet.  This is simply a jaw droppingly gorgeous Anamophic Widescreen Transfer (even with the light amount of aliasing throughout).   The Level of detail is in nearly all instances exceptionally sharp, and the proof is in the stiching....of the clothing.  When you see as much detail in a fabric weave as you can with this picture you know you're seeing DVD at some of it's finest. 
Even the diffused shots Eva Marie Saint are still very well detailed and captured beautifully.
Grain is essentially non existent and Colour Saturation is ever so good, but is only occasions a fraction too high.  Black level is very good, and allows for plently of shadow detail when required.
Spread over two layers of an RSDL DVD, the layer change occurs at 84:43 (chapter 30) in the middle of a scene, but with minor interuption.

AUDIO
The audio has been nicely cleaned up and presented here with a Dolby Digital 5.1 mix
Most of the dialogue is centre only, and is clean and clear throughout (though not with the same level of clarity as you'd expect from newer films).  Bernard Herrmann's music score nicely fills across the front soundstage with a little ambience thrown in for good measure. 
The Surround channels are not used to great effect, but do come to live once in a while.

EXTRAS
Some great extras here.

A good forty years after NBNW was made, Writer Ernest Lehman put down his pen and recorded an audio commentary. It may be slow moving, but he knows the film well and offers a few good anicdotes.

The icing on the cake however is the 2000 Desintation Hitchcock - "The Making of North By Northwest" Featurette entitled.  Hosted by Eva Saint Marie, this doco pretty much spills the beans on the whole film so DO NOT WATCH THIS FIRST!!.  It's a terrific companion piece for this DVD.

Touted as one of the best, if not the best esponage films, North By Northwest is not only incredibly witting, with great suspense, but some truly classic filmic moments.   As a DVD it has received stellar treatment.  Highly Recommended