According to http://elderscrolls.wikia.com/wiki/Nightingale_Hall: "On your first visit there is very little of interest to speak of inside Nightingale Hall aside from some bed rolls, two chests with some minor loot, and skill book. You can return later to find a few changes including a bookcase and nightstand with several interesting books." According to http://elderscrolls.wikia.com/wiki/Darkness_Returns: "After you speak to Karliah, Gallus' ghost will appear and they will speak shortly before he goes to the Evergloam. Karliah, then, goes back to Nightingale Hall. " According to http://www.uesp.net/wiki/Skyrim:Darkness_Returns: "You can now return to Nightingale Hall and use it as a home if you wish. Karliah will also live there." And under the bugs section of the same page: "On the PC, 360 & PS3 this quest will halt (after you are able to receive one of the three abilities) and Karliah has spoken to the ghost, her dialogue says she will return to Nightingail Hall, but she seems to bug out, staying there for 24 hours, then ends up in "Snow veil Sanctum" where she poisoned you in the last quest. She also states that a portal will exist in nightingail hall, but none is there, in fact, nothing changes at all. Brynjolf shows up in the thieves guild (with his old thieves guild gear on, not the nightingail gear) but just says "I'm busy talk to me later"."
Hi, ogrimtitan I am equally as disapppointed as you are, in fact, I was the one who added that last detail you copied from uesp.net... I found your post here trying to find some update to this whole issue. Strangely I'd like to add that even though I finished "Hard Answers", it popped back up as a quest I need to complete again when I went to the dwemer museum in markarth, I was excited and thought maybe they had patched it, but after going through the paces, it's still broken

Interestlingly enough though, karliah wasn't bugged out in the snow veil sanctum anymore, she was waiting in the inn where you turn in the notes copied onto the parchment. After going through all that dialogue she walks off and goes right back to the veil. I find it hard to swallow that they haven't fixed this crap, and I believe they won't, someone will have to write a mod outside of bethesda to fix it. That makes me view bethesda as cheap. They did the same thing in Oblivion. Only thing is they grossed so much $$$ off of this game you'd think they could stop being stingy and pay their dev team to work out these bugs.