Just beat the game. Apparently the epic, "certain point" I was talking about before actually was the last "mission". I use quotes because you don't really do too much - not to spoil anything.
Anyway, it was pretty good. The slideshow you guys were talking about wasn't really screenshots taken during your game - but rather canned footage that gets displayed based on things you do - at least, that's what I gathered, as I don't remember seeing those things directly. I dig that you can reload right after the final decision to make the "other" decision and see how the ending differs. I suspect the "200+ endings" are just different variations of the final dialog.
Now I'm not sure if I should reload from before I started the last mission to do all of the side-quests I didn't do, or just start over so I can get the achievements I missed. I'm not really looking forward to re-doing all the stuff, though. As far as gameplay time goes, it took me just under 21 hours to get the full story and a handful of sidequests, along with some basic exploration. I finished at level 20, but a chunk of that is because of the dialog glitch I mentioned before.
Overall, some interesting twists, pretty cool story, pretty good game. I'm a bit bothered that I found a sniper rifle during the final mission - I couldn't have gotten this earlier?
Oh, and also, I went the entire game without building a single item at the workbench. And unlike Oblivion, there's only 1 home you can own, and it's in Megaton, so don't blow that place up.