It takes about 60-80 hours to Plat RE 6 mainly due to a few trophies that require a lot of farming or replays to obtain. As for how hard it is, it really isn't all that difficult. Even the Pro mode trophy is pretty easy once you master the controls (it's no where near as hard as RE 5 Pro, No Hope difficulty is close though). It really just requires patience and a little bit of skill.
When facing a zombie apocalypse, don't join up with a group. Why? Because you'll end up blowing your own head off due to all the pointless drama caused within.
150 medals is not that hard to obtain,also the max skill points,especially if you are switching between modes like me. i'm just complete leon and chris campaign and i already have that medals trophies.For me , the most i hate is the "heirlorms" trophies that requires you to collect all 80 serpent emblems for it.