I've played this thing when it originally came out in JP, when English didn't work, and stumbled my way through up to the ending. Sticking my nose in the English enabled version, it does feel like it's running a little smoother, though for some reason, the skills feel weaker in some aspects... though that might just be me being used to my lvl 60 build that had all the shit bought and high level, if mostly random stated items.
That said, the only "Diablo-like" elements of this game is the item system... and honestly, even that is a stretch. Unless you want to compare it to how Diablo 3 was at the start, where the Legendaries and Sets were all around pretty shitty. The same applies here in my opinion, with very few exceptions looking impressive in any way. Likewise, it's hell to actually get items with stat combinations you actually want, making it difficult if not impossible to use a specific play-style you enjoy, and forcing you to adjust on the fly or just keep grinding levels and skills to compensate for the lack of stats on your gear.
That only takes you so far though.
Beyond that, the slave system is interesting, though I wish we had a list of possible bonuses.
So far, in the brief time I've played, I've seen an attack bonus, though I have no idea how strong it is, or if it's flat attack or percentage attack. I've also seen shop refresh discount, as well as shop items displayed. That second one seems pretty neat once you reach the point where you've maxed out your skills, because with just two slaves with that at level 3, you get a full page of stuff... out of which most is crap, obviously, but more rolls means more odds to actually get something decent.
As it is though, it doesn't feel worth it to spend money on store refreshes before you max out all the skills you actually care about in the skill tree....
In my case, that's most of them except for the one that makes you take extra damage while you have air-time. Sure, it makes you immune to movement impairing debuffs, but it's just asking for trouble seeing as you have no way to speed up your descent to better control your air-time.