Made all the right improvements over MMZ1. Triple Rod doesn't feel pointless (though the swinging mechanic is a bit finicky), cyber elves don't require hours of grinding just to use, weapons don't have more levels than a Pokemon game, Forms and EX Skills give an actual reason for the bosses outside of the elemental chip rock-paper-scissors mechanic, missions are a bit more open-ended an have actual goals within them outside of "get to end and fight boss." That said, the home base feels a bit superfluous and some of the bosses hit way too hard even with upgrades for lives-based game. Checkpoints in the Legacy Collection make a big difference. And again, I would say they wanted to encourage backtracking but never really figured it out. You can go back to the stages after clearing them, but there's barely any reason to and some even don't have any enemies anymore.
I really like the inclusion of the guardians from MMZ1. You fight them once and they're familiar with some minor tweaks as regular level-end bosses. Same elemental weaknesses and everything. Which makes sense, they're still the same entity. Their allegiances have changed but they're still adversarial. It all makes sense. You fight them again later in another form in a boss rush, which while still having the same weakness is a good change-up while also a good narrative twist. I was a little wary they'd bring them back for no reason but I think they did it really well.
I really like the inclusion of the guardians from MMZ1. You fight them once and they're familiar with some minor tweaks as regular level-end bosses. Same elemental weaknesses and everything. Which makes sense, they're still the same entity. Their allegiances have changed but they're still adversarial. It all makes sense. You fight them again later in another form in a boss rush, which while still having the same weakness is a good change-up while also a good narrative twist. I was a little wary they'd bring them back for no reason but I think they did it really well.