Incredibly dull, and offers nothing to keep one invested. I stopped playing after the first dungeon. (which I basically had to force myself to complete) Furthermore, the character movesets are overly mathy and lack personality, with various clauses and buffs added to each of your attacks with little in the way of discernable thematic justification. Presumably this was done in order to cram as much complexity into the battles as humanly possible at the expense of flavor and immersion, but that's not a very good design approach, not to mention you run the risk of leaving players mentally worn out after only a few battles.

Sleep inducing dungeon grind.

EDIT: The cutscene involving the diplomat guy who tries to woo the crowd when giving a speech and who critiques the temple's design afterward (with Vaan not having any of it) is surprisingly nuanced writing by videogame standards even taken entirely on its own, but you'd think if the folks at SE were really going for intelligent/mature they wouldn't sandwich that scene in between gratuitous crotch shots, nor would there be an inexplicable and hokey "Congratulations!" screen after the first boss, (Why does nobody ever talk about this? The other bosses don't even have it, making it doubly bizarre) or that the game's hub world and primary setting wouldn't be nearly as forgettable and confusing as it is, and I would have also liked it if they could've explained the job system better instead of forcing you to just choose one without elaboration up front, and without any elaboration after the fact. (Or would that make the game less "smart"?)

For that matter I have no investment in the characters. Fran and Balthier are like one dimensional tropes, I consider them 'cool' but my like of them pretty much stops there.

No leveling, only eight playable characters (half of which are clones), bad menu design makes it hard to tell at a glance which skills you have and haven't purchased, and a hub world that is horrendously designed that pretty much mandates that you wander aimlessly until you find what you were looking for. To top it all off, the gameplay outside of battles (exploration, etc) is excruciating. There's a tremendous amount of tedium involved in making sure you pick up all collectibles along the way, so you don't have to do the entire world over again afterwards. To rub salt in the wound, you're actually forced to play through each world in its entirety a minimum of two times, because some of the items require abilities that you don't attain until later.

There's hardly any motivation to keep playing after the main story is complete (thereby making the game quite short) and it doesn't help that the difficulty hits a massive spike right at that point. The various gameplay styles are also hit or miss. But perhaps the worst thing of all is that the story doesn't involve Undergrounders, which is like 50% of the series's charm.

EDIT: After revisiting the game I've started to realize how much it is bad and I hate it. All the menus from the title screen to the world map to the attraction specific screens are outright terrible not to mention slow. The concierge that greets you at every attraction is super obnoxious, always making me instantly regret deciding to get back into the action. What's more is that this screen doesn't even seem to lay out clearly (if at all) whether you actually completed the attraction, only whether you've attempted it. (meaning, it will display your best score, but that doesn't tell you much, since that score could have been a failed run.) I am absolutely repelled from playing the game any further. I've begun to strongly suspect that the game was never actually good, but happened to be easy enough so that there wasn't much stopping me from breezing through the main story before the flaws and lack of charm began to take their toll.

I like Mr. Driller, but this entry is not a good example of it. I'm honestly shocked by this because I always assumed this one to be the holy grail of the series.