I mostly like it. What i do not like, though:
1) Prismatic Shard find chance got lowered, from a couple of sources, while now they are needed in bigger number (one more tool to enchant)
2) Dungeons changed a little bit. While this is mostly a good thing for spice and variety's sake, Skull Cavern is now pointless to dwell in when you first unlock it, because no iridium nodes spawn in early levels anymore.
3) 1.6.4 made Mystery Boxes to appear less frequently. This is very inconvenient, since they have a pretty large item pool and the useful items you need, are already challenging to come by.
4) Transitioning from 1.6.2 to 1.6.3 on one save file, broke certain things, one of them crucial for the game. I am afraid to slowly update the game on the go one by one subversion, in fear of other things breaking, too. Instead, i am eagerly anticipating the very final, solid, safe version and to find the Book of Mysteries, first!
Other than those, all is well!