Decomposer's attack patterns have been noticeably changed, hopefully making the fight more engaging and fun.
The Frostfire Pineapple experience has been improved as well. Its dungeon now consists of a single room with a summoning altar, without any of the unnecessary extra rooms.
The pineapplemental's attack patterns have been changed as well, and are a bit more interesting than before. The boss has a 100% chance to drop an accessory called "A bottle of ice and fire", which summons a miniature version of itself.
On another note, a very subtle bloom effect has been added to the game. The colors should be a bit more vibrant and smooth, the dark environments will be slightly less dark, and light sources will be more effective at providing light.
And lastly, combat abilities have been balanced to be more or less equally viable. All three base abilities can be unlocked before fighting any boss, and all "secondary attacks" require defeating the Metal Core.
Since Slime spear and Flamethrower are harder to use and have a higher skill ceiling, these skills will have a higher damage output when used correctly - but the slimethrower is still a perfectly viable option if that's your cup of tea.