MH3 is not really similar to either of those two games. I've never played the MH3 demo, so I wonder if it's too short to properly demonstrate the appeal of the game.
That said, MH3 is a very niche game that didn't find much appeal outside of Japan so if you didn't like it I wouldn't be surprised. The game mechanics are pretty terrible and clunky. The game has almost no story. The game is only appealing to players who love to grind/farm and not ask why. (I loved it )
I know that Dynasty Warriors is more of a scenario-based game, which isn't like Monster Hunter. However, it's more of the
look of the game that reminded me of Dynasty Warriors. The characters had the sort of flamboyant outfits with somewhat ridiculous weapons, which is very similar to a Dynasty Warriors game. The camera angle also looks to be very similar, and I was in this snowy locale, which reminded me of one of the snowy maps in the last Dynasty Warriors that I played.
I think I mentioned Devil May Cry because that's also a Capcom third-person combat game, but I don't think that's the best example. If I were to choose a Capcom game that it reminded me the most of, it would probably be Dragon's Dogma. Man, that game is
BORING. I got it for free through PlayStation Plus, and ugh... I had to push myself to play past the opening!
*slash slash slash* "Are these attacks even doing anything?"
Although, my biggest qualm with Monster Hunter might have been mentioned by you -- the game mechanics being clunky. Although, my qualms lie mostly with the combat. I just find it odd that the people that made Devil May Cry have an issue creating a game with nice, fast-paced combat. My biggest complaint was probably with the whole sheathing/unsheathing of the weapon and dodging. Also, it didn't seem like you could use items until your weapons were sheathed.
I do normally enjoy grind-y games, but unfortunately, that was not one of them.