I'm tired and my thoughts may not be completely coherent, but my thoughts are here all the same.
Starting from v4's content, the bosses in this game really start to become needlessly prolonged. The difficulty is in a good place, I think, because there's a large emphasis on not getting hit, but it is artificially padded out by the insane amount of health the bosses are packing. Couple this with the how quickly and erratically some of these bosses move around or how much shit they throw at you in such little time, and what once was about avoiding enemy fire while dishing out your own becomes an arduous battle of endurance. Some of the bigger offenders are the Genesis Unit, Bass, the Mega Mech Shark and accompanying Changkey Dragon, and at the very top of the list, Quint.
Quint is a pretty fun fight for the first phase and the first phase alone. His other four phases are grueling and overstay their welcome by a long shot. Yes, I get that he's a superboss, and the spectacle is very impressive (the nods to MM10 and MMX1 had me geeking and its likeness to Shadow's boss fight from Sonic Boom: Rise of Lyric is especially cheeky), but 80% of that fight is simply not fun. While dodging his attacks is part of the thrill, to consistently and flawlessly keep that up for five long phases takes its toll on one's psyche. I honestly believe that the boss would be significantly better if he had a fraction of the health he currently has.
This rationality applies to most of the newer bosses. I'm not saying they should be a walk in the park, but ye gods, I think some of this stuff should be re-examined.
Barring that issue, this expansion is a great success. The maps are top notch, the weapons all feel good but still feel relatively tame, the spritework is gorgeous, and the new music is lovely. Major kudos to the dev team.
I'm also grateful for the opportunity to work on a map for this expansion: Freeman and I are responsible for bringing you all the new and improved MM4DIV and I'm super happy with how it came out and how well it's been received. It has definitely been a good learning experience for me.
Dr. Wily making breakfast and Auto's police chase had me laughing harder than I think I've ever laughed at this game. Consider it a success.