I'm actually thrilled about this. I was thinking recently about how much they cut out of "Order of the Phoenix." It was the longest book (up until Hallows) but the shortest film, and I could not help but feel a lot was missing from the film.
With Hallows, since it is the final story and it ties everything else together, I'm quite excited that it'll be two films. I hope they are each 2 and a half hours long.
And quite a bit did happen that is best left uncut. The opening with the final talk between Harry and the Dursleys will take some time, as will the action sequence of "the seven Potters" and the Death of Mad Eye Moody. The, the delivery of Dumbledore's will by Scrimgeour, the uncomfortable conversation between Harry and Rufus, and the climactic wedding of Bill Weasley and Fleur Delacour.
That's almost an hour right there.
Then you've got the confrontation with Kreacher and Lupin at Grimmauld place, the revalation of who R.A.B. is, and sneaking into the Ministry to infiltrate Umbridge's office. With the important subplot of saving the two ministry workers who are half-bloods still in tact, and the information that the Ministry has a fake Griffindor's Sword.
Another twenty minutes. Maybe thirty if they give Lupin time.
Then you've got the tension between Ron and Harry, the switching off of the locket horcrux, and the also very climactic and interesting excavation of Godric's Hollow, with the grave of Ignotus Peverell and the attack by Nagini. Follow that up with the Silver Doe, Ron's Return, and the destruction of the locket. Somewhere in there the exposition of "The Life and Lies of Albus Dumbledore" by Rita Skeeter. There's damn sure 40 minutes there. That's upwards of 2 hours, 10 minutes there. First film over.
Second film begins with a recap (5 minutes). First scene is the trip to meet Xenophilious Lovegood to ask about Peverell's symbol (and the info that Voldemort's name is now taboo and summons Death Eaters). The story of the Deathly Hallows, and the arrival of The Death Eaters, including the explosion of Xeno's home. 15 minutes.
Then, 5 minutes of plot exposition at the three figure it all out, and the capture of them by Greyback and the Death Eaters. Add in the torture of Hermoine by Bellatrix, and arrival of Dobby, the meeting of Ollivander, the death of Wormtail, the escape, and the death and burial of Dobby. 25 minutes there.
The huge break in at Gringott's, the dragon, the issue with the Goblins, and Harry's mental connection to reveal that a Horcrux is at the school. That will take 20 minutes.
Flash forward to Hogsmede Inn and the meeting of Aberforth, the story of their family and Gellert Grindenwald, the meeting of Neville and Luna in the mirror, the discovery of the Lost Diadem of Ravenclaw, the battle with Crabbe, Goyle, and Malfoy, and the scene where Harry saves Malfoy's life. 30 more minutes.
Then, you have to devote ample time to the battle scene of The War at Hogwarts, the trip to the Shreiking Shack, and the death of Snape. From there, you'll need a while for Snape's memories in the Penseive - that ties the entire plot of all 7 books together.
From there, the talk with Neville about Nagini and the use of the Resurrection Stone to speak to Mom and Dad, before Voldemort kills Harry. King's Cross station, the talk with Dumbledore, the beheading of Nagini by Neville, and the final battle between Voldemort and Harry. From Snape to here, you've got an hour.
Then, 15 minutes for the epilouge.
Yeah, two films!