Skyrim has a rather clunky battle system, but otherwise, I can't really see his point. Skyrim's a pretty good game, if you're looking for exploration and screwing around in a massive world rather than storyline. I mean, who honestly cares about the storyline of Skyrim. Hell, most just want to Fus Ro Dah spiders off cliffs.
BF3 is a good game. It has impressive graphics, and actually requires a degree of skill, teamwork, and coordination. I disagree with your friend on this point.
Minecraft might be a waste of time, but so is CoD. First off, Minecraft is a survival RPG, where you can sorta screw around or make fantastic landscapes. CoD has less longevity, because you can't really make your own world in CoD. The only replayability for that is prestige and loving about on the multiplayer.