Well, if its the LAST cutscene thats only 90 minutes long, then I think thats a little more acceptable. Its gotta have a great ending without any plotholes and with all the loose ends tied up right? I bet 75% is going to be Kojima pulling stuff out of his ass to explain the events of MGS2 a little more in depth.
It's been a while since I played it, but aside from a couple of lingering questions regarding the final boss, I thought that the "virtuosity" explanation took care of most of the issues.