I just picked up the GOTY edition and was wondering what happens upon completion of the main quest line. Does it just end like FO:NV? Should I do everything else before the last mission of the main quest?

Since you have the game of year edition it should transition straight into the Broken Steel expansion.

If you have Broken Steel installed you can keep playing.

Unless you don't install Broken Steel, then it will just end like New Vegas.

Cool, thanks for the help. BTW I'm enjoying FO3 way more than NV, best ten bucks I ever spent!

Just in case it doesn't get fixed, which I seriously doubt, there's plenty of cues that the final mission is just that so you have to wrap up everything else. Save before agreeing to it, then see the finale & jump back to the save & go run around the rest of the world. Still think NV is better but barely, both are great fun & GLHB!

If I remember correctly the main quest line in FO3 is much shorter than in NV. You can roll through it very quickly and then be stuck in the awkward spot of almost having finished the game and then running off to explore everywhere. I'd recommend finishing all your exploration south of the Potomac before you go into the Capital Mall. The game's story feels more cohesive that way.