There's a lot wrong with the Matrix chapter in SR5. Many things are too vague, some things are simply omitted, some things don't work in ways any slightly familiar with computing can understand, and basically there's a LOT of frustration in running a decker or Technomancer in SR5, to the point that I won't run the game with those characters anymore.
I noticed recently that the Data Trails book has been finally been released, which I was looking forward to very much before I became jaded with SR5's Matrix woes. Does Data Trails do anything to improve the state of the Matrix rules, or does it just pile new options onto a wobbly base? Part of me really wants to buy it, but I have basically zero confidence that it will ever see use at my tables.
In particular, does it answer these questions:
Can a deck that's not running a persona be a master over a deck that is?
Can physical objects slaved to a host be accessed from within that host?
Can a rich enough decker run their own host?
There are certainly more questions I have, but these are the ones I can think of off the top of my head (and with the help of the Similar Questions sidebar).