You know, for as much as I like text adventures and as influential as they were in my development as a programmer, it occurs to me that I've never actually
finished any of the classic-era text adventures (with one exception).
I've gotten pretty far into Colossal Cave Adventure, the first Zork game, and Adventureland. I've finished some more recent ones, in no small part because modern ones tend to be far, far easier, but if it was made before the year 2000... yeah, I probably never finished it.
The only one I've ever finished was Adventure in Time, and that only because I stumbled across it again 20-something years after I first played it and decided I was more curious to see how it played out than to actually solve the puzzles on my own.
There's an argument to be made that
Portal (not the Valve game) is a text adventure, and I did finish that. But it's not really the same thing, even disregarding the difference in user interface conventions -- if the game were totally text-driven instead of having a GUI, it still wouldn't quite be the same genre. (That said, I highly, highly recommend it. And then once you finish the game, find the book it's based on and read that because it includes some extra information that wasn't included in the game. Don't do it the other way around.)