There are no problems at all, as long as you use the Unofficial patches.
They are a blessing...
If you're waiting for Beth themselves to fix all the issues...?
Don't bother - the game's been out for a year and a half and Beth is just now getting to issues the USKP fixed a year ago!
I have played two complete playthroughs (1200 hours) with no issues at all, thanks to the Unofficial Patches.
Dragonborn is fantastic!
But thank gawd for the Unofficial Dragonborn patch - that's all I can say.

The DLC is pretty good, but as usual it's not without bugs. Had to start a new playthrough after using TES5EDIT to clean out the mod's, even the official DLC's for conflicts. My first character through Dragonborn hit a few bugs, like the inability to use the black books to return to Solestheim after visiting Apocrypha, then the main questline couldn't be completed because the main boss doesn't absorb dragon souls during the final fight, making it impossible to complete the final part of the main quest. It would be much more helpfull if the main advice given in almost every situation wasn't "Turn off all user made mod's and start a vanilla playthrough from scratch". I know Bethesda can't possibily fix all problems with mods, but allowing people to use mod's then saying to not use them because they might conflict with official DLC can seem a bit contrarian. I really wish sombody could come up with a list of which specific mod's are causing these conflicts instead of just telling everyone to turn off all unoficial mods in order to be able to finish the official DLC's. Never had these kinds of problems in a DLC for Skyrim before Dragonborn. I like the official DLC's, but there has to be a better solution than always playing vanilla all the time.