Yeah I don't disagree with Segata. There are a lot of people who enjoyed it and others who didn't. I just tend to be more vocal.
It's a competently made rpg with good graphics and sound. But here are my problems with the game:
1. It's subjective, but I didn't care for the story much. So I didn't have a drive to see what happens next.
2. The battle system is very standard and a little slow (faster than 8, much slower than the 2d ones). The one thing that makes DQIX's battle system unique is the job system. Unfortunately for me personally the game did not have a job system. The job system IIRC resets your character back to lvl.1, I changed job ONCE with one character midway through the game and it took him until the final boss to catch up to the other characters level-wise. Meanwhile for the entire 2nd half of the game he had a low HP, low DEF and low ATK until pretty far in, making him useless until the end. This means if you get to a boss that you are stuck against and you realize you have the wrong jobs for the boss, you can't just switch jobs like FFX-2 or 4WoL or switch demons in SMT to re-strategize. If you do that your characters will drop to lvl.1 and it'll take hours to grind them back up to the point where they even have enough HP & DEF to survive the boss's attack. So basically if you get stuck on a boss you can A. Grind or B. Change jobs and grind EVEN MORE, which kind of takes away any incentive to change jobs. So yeah, for me it was like the game had no job system and was just a by the books battle system that wasn't quick or had unique aspects.
*edit, also another negative against changing jobs was you don't keep most of your good skills/spells when you change. So it's not even like you can build up a cool character with all these skills/spells from various jobs.
3. There's not much of a world to explore. The main story leads your around from island to continent. But since you never get a flying vehicle your world exploration feels pretty limited. I don't remember finding any real meaty optional things in the main game.
3. You make all your party characters so they have no dialogue and they are not real characters. The only real character in the story is your lead + the NPCs. DQV was like this too, but there were other characters with your family. No cute monsters in your party either.
So yeah, without a story to drive me to play or a battle system that made me want to fight there just wasn't much motivation to keep playing other than just to get it done. The dungeons were fun to explore, but that was about it.
And yeah, after I beat the game I tried a bunch of times to beat the post-game boss to get the flying vehicle and read some strategies online and the consensus was that it was just impossible for my team because the boss's big attack would wipe out my whole party instantly. So the choice was to grind. Not just a level or two, but A LOT for several hours or more. I weighed the idea of using my time to grind and the result of getting a flying machine to fly around the world to get more quests and optional bosses where I would need to grind more...and I decided that I was finished with the game.
I don't care for Level-5 DQs much, but to my knowledge DQ8 is still the only jrpg ever to have a real 3d overworld like a wrpg but with jrpg map design. That was exciting enough to drive me through DQ8 to explore it all. DQ9 didn't really have anything to do the same.
I still look forward to DQ6r since I absolutely love non-L5 DQ.