I'll be the first to admit I know nothing about the Monster Hunter games beyond the fact they're massive here in Japan and you fight and hunt monsters. This is not through any level of ignorance, either. It's just the series never had the same level of immediate expansion as so many other Japanese games. There's no story, just a quest - hunt and fight monsters in order to craft tools and armour to do it even better.
Thankfully, the Wii update to the game, Monster Hunter Tri, addresses many of the nagging problems people who didn't feel compelled to log 1000 hours had with it, beginning first and foremost with story. There's a definitive story here, apparently, and it's already proving even more successful as a result with MHT flying off storeshelves all over Japan. There's also the idea that people couldn't simply jump into the main game and therefore had to play through a heady and *boring* tutorial that lasted far too long, as suggested by fans, post-release, which has been addressed with the inclusion of a tutorial attached and definitively linked to the game's new story mode. However, this could also be attributed to Monster Hunter Tri's next big change - and that's accessible online, and yes, that's Wii online.