I bought this game at launch expecting it to be DQ8-caliber for the price.
When I found out what it was, I wasn't put off by it, I played it for an hour or two a night for a week or so and was able to beat the boss and go onto the extra content that followed.
I cleared through the first wave of extra monsters with relative ease. Then started the second wave. The curve required in levels from the previous point to the next was just insane. I have no problem with needing to grind a little to continue, but this leap needed me to just about double my levels to continue. I shelved the game at that point.
I may go back to it, play it through again and then stop at where I stopped once before. But I doubt I'll be able to set aside as much time that's needed to grind that many levels, even with the king metal slime, or whatever it was. (Like I said, this was all a week or two after launch, so it's been a while.)