In terms of a story ending, it's no more than a 4 out of 10.
In terms of a manga story ending, it's a solid 7.
Then again, I haven't read the last 100 or so chapters, so I don't know if this was built-up-to in any way, which could change things, in theory.
I'm assuming that there will be at least one volume extra that will tie up some loose ends, jump ahead in time, and give us some sort of "where are they now?" for closure.