I love this manga, but i want to say two things, possible spoilers:
1. The last chapters feel a bit rushed compared to the whole treasure map arc and some characters acted a bit different, as if the previus story didn't happen or they were sightly rewritten, it feels like this was meant to be a second half for this story but Tezuka either decided or was forced to end the manga earlier and compressed the whole arc in three chapters.
2. This is not a complaint, but I would have liked to see Puchi and Uru see their mother in the same way as Ben did in chapter 6, Puchi would have been given more time in the story (she is barely mentioned in volume 2) and would have given a little more development to that last arc for Uru, which as I said seems a bit rushed to me.