Are there multiple endings? Maybe that would help.. STALKER had some crappy endings... although Bethesda hasn't really done multiple endings in the past.....
4, 5 if you count the different speech. But they're all pretty much the same shit.
1. Good: You do it and you're good
1a. Good: You do it and you're bad
2. Bad: You say you'll do it but don't
3. Coward: You let her do it
4. Corrupt: You do it but *SPOILER*plant the virus*SPOILER*
And that's it. The end, no more exploring, no more roaming. Just ends.