It was quite prone to crashing-to-desktop and certain PC configurations had bizarre graphics issues, but I did play through it on hardcore in the week of release and had a great time with it. Just needed to quicksave a lot.

The kind of bugs that it did not have a lot of were quest bugs. Bethesda's own games are 'wide but shallow', and very few quests in the world seem to interlink with each other, but despite that, they're very easy to break accidentally, or cannot be completed due to flag issues. Oblivion managed to wrangle up a complex plot with tonnes of interrelated parts, and it mostly just worked.

What F:NV could have been if it had been made in a good engine... Most of the times where it got dinged in review scores were for bugginess and instability. Trying to build a castle upon sand; there's only so much you can do before all the cracks appear.

That day one experience was the only thing that made it feel like a Bethesda game. I had that exact same experience in Daggerfall, Morrowing, Oblivion, and Fallout 3.