THIS POST CONTAINS SPOILERS!!!
Well, if someone has ALL the hallows, they're virtually invincible or something. I can't remember the exact details. But I too think that to introduce them, especially in the very last book, was pretty random. I wish there'd been small hints or references to them throughout the series rather than them being introduced at the last minute with no prior mention. Same with the horcruxes. They should have been vaguely alluded to in the first 4 books. But I guess J K Rowling didn't initially know where she was going with it, so...
IMO the deathly hallows are a plot device. And two of them just coincidentally happen to be the snitch and Harry's invisibility cloak. It's too easy.
Still, I love Harry Potter and am very glad that I grew up in this generation and got to experience this wonderful phenomenon. The only thing I don't like is the epilogue and the last sentence. IMO it was completely unnecessary and the book would have been better without it. It's so cliche, what with him calling the kids Lily, James, and Albus Severus *shudders*. I think the epilogue's main purpose was to wrap the story up so that no more books could be written.
---------- Post added at 10:46 PM ---------- Previous post was at 10:44 PM ----------
Oh, and in reading the 7th book, it took me so long to get my head around why Harry didn't die. And the whole being naked on King's Cross Station with Dumbledore thing? Talk about weird. 😀