Yes but with a few FYI's and 1 exception.
Items are safe for the most part but can and do tend to get kicked around either by you or house guests. Items when first dropped in your house create a "spawn trigger point" this meaning
Say I drop a nice helmet to display on some shelf, so I drop it on the floor then
Drag and drop it onto the shelf,then exit the house and come back later.
You will now find the helmet not on the shelf where you moved it but in the place it first was dropped. Now if you drag and drop from this point it should stay on the shelf or whereever you decide to place it, rule being redecorate with the item after you have initially dropped it,exited and returned. FYI on rare occasions even this rule breaks and the first drop and drag holds ,so go figure :)
Exceptions to both the safe and placement rules.
When you own more than 1 house and you have say already redecorated using the rules above
And then bought another house and did the same,THEN decide to go visit your first house you may find things or items out of place - even sometimes finding the whole house exploded. Most items regardless of whether you ever touched them or not get thrown everywhere.
This is because of a "Spacial Placement BUG" which sometimes links owned property.
The last is the safe exception.
There are times and I have personally had this happen where you drop an item even a
unique and irreplaceable item down in your house and it will either go poof then and
There or right after you exit and re-enter said house. This has happened when only one house is owned as well as when multiple houses are owned.
It tends to happen with smaller items but some large items i.e. swords or shields or staff.
This seems to be a rare event but like I said it happened to me so to define rare,
I've played over 500hrs real time and have so much stuff whose to say, I only noticed
because it was a rare book and I was placing it for display on a coffee table in Whiterun and when I reentered it was gone,this being after I dropped it,then exited reentered and placed it. This is the only item I know I have had go poof.
I hope this helped