I only had some small studding problems pre-patch (which where taken care of by using a D3d9.ill file, also had some problems and had to reinstall when the patch was released due to the modification i did to the Fallout_Default.INI file (you would think i would have just made a copy b4 i modded, but i never learn

)
any way since the patch i haven't had any problems at all, not even 1 CTD and i am running many mods (around 15 .esp, would be more like 35, but i just decide to combine all the mods that add only 1 or 2 items).
there are still some buggy quests i would imagine but i haven't played all the quest yet so i cant say that for sure, but over all it's very playable and enjoyable.
i am not sure about some of the problems that others are reporting in other areas of the forums, i haven't had any though.