Reasoned Schemer 2nd Edition

[Rick Moynihan]

I've had a treasured copy of the reasoned schemer for many years, and recently noticed that there's a second edition.

Can anyone tell me what's new?  And whether it's worth buying if you have a first edition copy?

Is the main difference that it's based on an implementation of microkanren rather than minikanren? 

Does microkanren have different semantics to minikanren?  I'd initially thought it was mainly just a smaller and simpler implementation, however I've also seen comments indicating it changes the search strategy.  Any pointers to resources discussing the differences between the two would also be greatly appreciated.

R.