Gaijin Hunter, who's been the best-known Monster Hunter Youtuber for some time now, just put up this video about the end-game content:
Seems like a pretty good system to me. MHW's "investigations" are much like MH4U's "guild quests," except that you don't level them up, and they can be used a limited number of times, meaning you'll always be looking for more. It provides monsters that are still challenging even after getting all the equipment you want, and good rewards for continuing to grind it out, if you're so inclined. I'm excited to start messing around with this stuff!