My experience, vanilla is pretty playable depending on how you go through the world.
Don't touch any of the DLC. Once you add that it pretty much kills everything.
If you really want to play it like its meant to be it doesn't work very well. In order to extend the gameplay it helps to interact with the world minimally and clean up as you go along. Pick up stuff and sell it all to vendors.
Create a LOT of saves.
If you leave the autosaves on prepare for freezing. I find that autosave on rest/wait is useless so I disable that one. For moving between cells I try and check the PS3 HD light and if it looks really busy I wait to move. Because autosave on travel is often the culprit of freezing.
The framerate svcks in a lot of places. But the storylines in FONV have been worth it to me.
And no, they are not going to fix it. I asked Gstaff directly about FONV and FO3 and I got a 'we dont give a [censored] and have moved on' kind of answer.