On your suggestion, I’ve read Gregor the Overlander and I am very glad that I did. At this point I don’t know if love it, but I certainly don’t hate it and I want to read further into the series.
You were spot on about the characters! Each was textured and unique with a good arc and progression. So much depth and dimension! That said, I’m not really attached to any of them yet but it’s only the first book.
The Underlands itself was interesting but it didn’t strike me as something special or unique. Maybe I’ve just read too much youth fantasy. I think I just need more info and details about what life there is like since we mostly see things in passing or standing next to royalty. I guess what I’m saying is that we’re only given a superficial understanding of the Underlands and I want more. This gels mostly with what you said about not knowing where or how far away things are.
In summary, it’s a good book. I’d like to see where it goes.