Ok, here's a short summary:
Harry, Ron and Hermoine have left Hogwars, attended Bill & Fleur's wedding where they learned the Ministry of Magic had fallen and Voldemort is now in charge, they receive three heirlooms from Dumbledore i.e. Harry gets Griffendor's sword [though its not handed to him since it has disappeared], Hermoine gets a children's book about the Deathly Hallows and Ron gets the deluminator.
As part of their quest for the Horcruxes, they break into the Ministry, then they are on the run for months from Death Eaters. Ron gets angry and hopeless and leaves them for a while, Harry & Hermoine go to Godric's Hollow and learn some stuff about Dumbledore, Ron rejoins them, they are captured by Death Eaters and Hermoine is tortured by Bellatrix, they escape to Shell Cottage, where Bill and Fleur lives.
They break into Bellatrix's vault in Gringotts with help from a goblin to get a horcrux and escape on a dragon, they go to Hogsmead village where they meet Dumbledore's brother Aberfoth who help them enter Hogwarts. There they get another horcrux and destroys it. Now only Nagini and Harry remain as the final two horcruxes. Harry also learns the truth about Snape, who was never a traitor and worked for Dumbledore all along, who ordered Snape to kill him.
Battle of Hogwarts where Death Eaters and Order of the Phoenix members battle each other, students and parents join in, mostly on the OotP side. Harry goes to sacrifice himself to Voldemort, who "kills" him but actually just killed the horcrux part of Harry. Also Harry couldn't die outright like that for two reasons i.e. he was master of all three the Deathly Hallows, thus master of death and also, Voldemort tried to kill him with the Elder Wand, of which Harry is master, and the wand won't work well against its true master.
So Harry lives again, returns to the Great Hall of Hogwarts and battles Voldemort in single combat. The Elder Wand backfires with Avada Kedavra and kills Voldemort.
Those that died are quite a lot i.e. Lupin, Tonks, Fred, Colin Creevey, Snape, Dobby, Hedwig, Mad Eye Mooney, and about 50 other people.
So there you have it. And why won't you read it? It is really good! [except for the cheesy epilogue].