They are not working for me they open and close but I cant put anything in them.

That's apparently normal. You have to manually put stuff in them.

My stuff was on the floor next to the display case after returning home.

Fail on Beths part.

Yea, in oblivion i could stuff display cases full of stuff (books, weapons, armor etc) and they would stay there until i moved them, or anywhere in my house for that matter, even after leaving the house a thousand times. I left items in my new hearthfire house once and found them all over the place with the cases i put them into closed and empty. So i have dozens of cases empty because I know they dont work like they did in oblivion. PLEASE FIX THIS BETHESDA... i love this game too much to bear this pain

Also getting lots of freezing issues, esspecially with armory. Took serana in there and game froze 3 times. Then hired a bard and got married, froze the instant I went in armory and now im afraid to even enter the armory. Dunno if the glitch is with armory or that wing of the house in general or maybe falkreath location is bugged..

Cant figure how to buy in Pale or Hjaalmarch, only falkreath was sent to me via letter from courier. visited both jarls for these locations - nothing. visited locations of where the houses would be judging by the trailer and there is nothing there.

I didnt like the way the wings of the house were organized. I really wanted a armory AND library, but they are two choices for one wing, therefore i have to choose between them. oh well. Love the addon, but is very fustrating. fix these bugs and it will be amazing

Only found one person to steward for me and that was the falkreath housecarl. I read that i should pick someone in the game who i really trust - my other housecarls? Serana? any random people ive done favors for? none of them would have the option of being steward. Im hopeful a game update will come soon

Then the engine got more complicated and all these issues started to pop up. Physics in this game needs to be re-written from scratch because it's terrible.

I should copy & paste this into a topic on these boards even though I can't take credit for it. It's a sticky on the GameFAQs Skyrim board and it's very helpful.

http://www.gamefaqs.com/boards/615803-the-elder-scrolls-v-skyrim/61718366

If you have a follower, you can ask them to be the steward, but the option only appears when at the house you've built.

As far as I know the display cases have always been buggy and I'm pretty sure they were almost unusable in Oblivion before someone created a proper display case mod.

This is most likely one of the bugs that will be fixed. Keep in mind all of this is new, they need time to work things out.