I'm not sure i thought TW1 was a hypefest, can't remember if i followed it that much though, what did they hype, the awesome AI?
Certain things are always hyped;
* AI. Bethesda even claimed Morrowind's AI was something out of the ordinary. And it really was, in a bad way. I never listen to what devs says about AI any longer, its always BS. It can be described quite vague like um, "it's awesome!" and you cant have it in numbers, which is perfect for the marketing hype machine
* Combat. This is always hyped, and almost never that satisfying. It's also vague.
* Graphics. Kind of hard to lie about, so this hype i can "buy".
* Size of the world and number of quests. This is also not really possible to lie about, since you often have it in numbers. If Betehsda would lie about the world size the whole community would make an uproar, they'd be sued to left and right, no doubt.
I don't think im that naive any longer, i certainly was as a "newbie" to computer games (i've been following games since the Commodore 64 period, so hype is hardly anything new to me.).
I'd love to hear your examples where devs has lied before about world size though, maybe it's more common than i think, but i doubt it.