Quite a lot has changed with the release of The Prisoner of Azkaban.
For Harry's 3rd adventure at Hogwarts, He and his pals (Hermoine and Ron) are now teenagers. Chris Columbus handed the reins over to director Alfonso (Y Tu Mama Tambien) Cuaron. The film is considerably darker, scarier and more sinister. And with the passing of Richard Harris, Michael [The Cook,The Thief, His Wife, and Her Lover] Gambon has taken on the role of Hogwarts beloved Head Master Wizard Dumbledore.
Even with all of these changes, the overall quality of the Harry Potter films has in no way been diminished. In fact, I personally believe this to be the best Harry Potter film to date.
With a few years of experience now under their belts, the quality of the acting from our 3 main heroes is far more polished than past outings. And Alfonso Cuaron also brings a new slant to the film's tone which is less cutesy than the last 2 films. This in fact caused a lot of controversy upon the initial submission of the Australian Office of Film and Literature Classification Board who slapped the film with an M15+ classification.
Warner immediately appealed the decision and after reconsideration, the OFLC dropped the rating back to the PG ( I mean if Jurassic Park can show a torso being ripped in half and get a PG rating, then so can the essentially bloodless Prisoner Of Azkaban).

This time around, our baddie is played by one of the silver screen's most reliable bad guys ever, Gary Oldman. Here he is Sirius Black, the man who ratted on Harry's Parents which resulted in their death. Sirius has escaped from Azkaban Prison and he's now after Harry to get revenge for his incarceration.

Seemingly safe within the confines of Hogwarts, Azkaban's prison guards, the completely nasty soul sucking Dementor's, are on the hunt for Sirius, and for some reason also have a very strong taste for Harry's soul.

As Harry and Co. learn of Sirius, they also start to uncover other more truths behind his parents death and that of Hogwarts residents.

As with each Harry Potter film, a new round of teachers are on the scene. Replacing the inept Professor Lockhart (played by the excellent Kenneth Branagh), as teacher of the dark arts is David Thewlis - Professor Lupin.
After saving Harry from a Dementor on the train trip back to school, Harry and Lupin strike a bond and Lupin becomes Harry's mentor where he teaches him a few new tricks that may help now that Sirius is on the loose.
Emma Thompson fills the 2nd new [comical] role as Sybill Trelawney, Hogwarts Devination Teacher (tea, crystal ball and palm reading for short). She's also a seeker and tends to channel spirits out the blue.

The regular teachers are also back, with Alan Rickman doing his grumpily best as Professor Snape, and Maggie Smith as Professor McGonagall. Although this time around, the character of McGonagall is seen considerably less, which is a little disheartening, seeing as she is such a great character.
As mentioned previously, Richard Harris was replaced with Michael Gambon, due to his untimely death. With Harris' portrayal of Dumbledore having such commanding presence in the film I was unsure how it would be possible to replace him so late in the game. Michael Gambon's portrayal is so vastly different to that of Harris's, yet he manages to make the role his own, while staying true to the character.

Harry's third year at Hogwart's is a rollercoaster road from start to finish. It's much darker and far more impactful than the past 2 outings. But with the growth of these characters and this world, it only makes sense that the tone of the film to would also make a natural progression.

VIDEO
In accordance to the tonal change of the story, this film's look now offers a darker more sinister appearance as well.
This 2.40:1 Anamorphic Widescreen Transfer is generally very pleasing, sans a few minor exceptions.
With the look of this film being considerably darker, shadow detail is excellent throughout and even in the darkest of scenes, I had no problem clearly seeing all that was needed to be seen. This can be attributed to not only a spot-on black level but also a phenominally clean print, one that is completely free of dirt, grime and grain. I would however recommend viewing this DVD in a totally darkened room for maximum effect.

Colour saturation is intentionally muted, and while not what i would consider lush and vibrant, is still highly impressive and consistent throughout.( I think it suits the film very well and couldn't imaging seeing this film any other way)
Sharpness is generally very natural without any signs of edge enhancement, but i did find image depth and detail to waver slightly from time to time.
A quick check of the bitrate levels showed an alarmingly high occurance of it being around the 5Mbit mark, which surprised me, given disc 1 essentially contains only a movie.
The TOTAL amount of space used on this DVD is only 6.07GIG, which leaves almost 2 GIG of unused space. Even so, there was absolutely no signs of major artifacting to be seen, but rather a slight softening to the image (primarily in wide shots that lack any extra fine detailing), which would help explain the lack of real image depth I was seeing from time to time .

Spread over 2 layers of an RSDL DVD, the layer change is very cleverly hidden during a scene change, that starts of near motionless. The layer change occurs during Ch 20 at 72:36, just as Prof. Snape lowers his wand.
On my Denon DVD player it was absolutely seemless, so i had to pull out the old Sony which shows you the layer change point. It also performed it incredibly quick, with only the briefest of pausing.
All in all this transfer will please most people, but I still think it could have looked even better (given that there's a considerable amount of unused space available)

AUDIO
Unlike the first 2 Harry Potter Films which were mixed for Dolby Surround EX, Harry 3 is only a Dolby Digital 5.1 soundtrack (encoded at 384kbps).
One a whole though, this is a terrific soundtrack and offers not only thunderous bass and excellent FX placement but also highly intelligable dialogue (even during the extremely quite passages).

Still, I would have liked for Warner to up the bitrate to 448kbps for that extra leg-room, as this is one soundtrack that truly deserves the best available reproduction.
The Quiddich match during Chapter 15 is an outstanding example of sound mixing and is demo quality, with firstrate surround sound usage, and bass attack.(it will really give you system a workout)

Subtle sound FX also come through with a great level of clarity and add greatly to experiencing this soundtrack.

EXTRAS
With The Marauder's Magical Map of Hogwarts as the backdrop, you make your selections based on locations around hogwarts.
The menus are fully interactive and there's a rather annoying voice over guy telling you to hurry up if you don't make a selection hastily. :)
The Menu selections can be a bit of a pain [personal gripe with menus] as after a selected feature finishes playing, the next feature is NOT selected by default.
Subtitles are also available on all the featurettes, which is something i'm pleased to see more of as time goes by.
Nearly all the featurettes included are presented in widescreen, which is great, but they are only 4x3 Letterboxed. More studios should be making the move to 16x9 Enhanced menus and extras now that there's really very little excuse (especially for latest release films).
While there are quite of lot of extras on offer I found myself wanting something with a bit more substance. But then again kids will no doubt have some fun with the games, etc, and they are the primary target for this DVD.