Yeah, I'm guessing the actual story will be around 30 hours, but with all the side missions and exploring it will be around 120, and then there is online--which I've heard you can design your own missions and R* has hundreds ready to go.
That is a crazy amount of content...I still don't see how all this is going to be just 18gb...with all the audio alone it seems impossible. Maybe the initial download is 18gb and then it unpacks or connects to R* servers to install more data...I just don't see it all being only 18gb.
The reason I'm starting this up is because I have it preordered but I may just buy it digitally, but I'm scared of the install time! I called where I have it preordered to make sure they are doing the midnight release and they said, "Of course, we have about 300 preorders!" that is going to take forever unless I go early and wait in line, spending more time OR I can get it digitally and wait until 3am EST to start the download (just 18gb...not bad) but then the install which I'm guessing will take longer than it should because of R* using compression to make the file smaller than it should be--maybe I'm way off base here, but that's the only way I see it being just 18gb. Decisions, decisions!