I just got it as a gift from my insanely wealthy aunt, and so far my biggest complaint is WHERE IN THE NAME OF KOJI KONDO IS THE MUSIC, CAPCOM? It's just so blatantly missing given the engaging but honestly repetitive gameplay- I'm sitting there, waiting for the fish to bite, or for the Kelbi that only seem to have horns 3 percent of the time to respawn, and I'm thinking: hey, where's the music? Where's the lush orchestral soundtrack to accompany these epic landscapes? It's hard to ignore the silence that dogs you on long treks. Of course, I've only done like four quests, so maybe the other areas of the game will have some sort of soundtrack, but it's still really annoying.
Secondly are the nagging resemblances to MMOs- the grinding for resources, gold and armor, the quests that always fall into some pattern of "kill x enemies" or "kill enemy Y until it drops body part Z". Yahtzee put it best when he summarized it as "all of the worst parts of mummorpuguhs squished into a huge, gelatinous mass". But it's weird to see the developers claims- that it's an integral part of the Monster Hunter experience that really works all together- and then see those claims come totally true. I really really like Tri, despite always hating all of the grind and item management and quest annoyances every step of the way. It's probably the combat system, the monster AI, the slow but noticeable progression. Everything sort of works, in a twisted addicting way.
So yeah, it's sort of a paradox- it's simultaneously incredibly difficult to like, and almost impossible to not love. It's freaking weird and I'm really suspicious about the psychology of it all, but it ends up fun, somehow.