Better than the first one, and not just because I'm totally weak for nautical fantasy.
Huge increase in female characters, definite increase in non-straight characters. The boys being useless and getting into shenanigans. Bad-ass mom character. More scuzzy fantasy - my favourite.
The Lies of Locke Lamora felt like it needed tightening up at the seams, and while the nautical terminology and junk (whether it's legit or not) might be a bit much to swallow for some, Red Seas Under Red Skies felt far more streamlined than the first one.
High hopes for the Republic of Thieves.