I will preface this by saying that it's been a while since I played the original Eiyuu Senki, so the comparisons between the two games will be minimal. I'll be reviewing this game on its own and tell you what to expect, so if you see something that makes you think, "But it was the same in the original!" it doesn't matter.
If I have so many things to complain about, why not give it a lower score? Because I'm not dishonest. It's undeniable that this is a polished game. The art is amazing, the engine is well-optimized and the voice acting is flawless—flawless, I tell you. I've never spent so much time researching VAs before, because almost every VA in this game is just fantastic. If you get past the bullshit bosses or simply ignore them completely, the gameplay is also polished. And while there are many annoying characters, some new characters are genuinely great additions that make previously uninteresting countries more interesting, like Cleopatra, for example. She's my favorite new character, and her sex scene is very good. Would've been perfect if we also got a threesome with her and Tutankhamun, but anyway.
TL;DR: Unremarkable and cliché story, terrible writing, annoying characters, better gameplay than the original but with many bullshit bosses, a lot of underwhelming sex scenes, rushed events, some characters have very few scenes, great art, great voice acting. Can be an enjoyable experience.
Many of my complaints are just my opinion, and that's fine. I wasted a lot of time on this game, time that could've been much more enjoyable if not for Masamune, Billy and the protagonist. Thus, I don't mind writing a wall of text to vent my frustration. I recommend that you play the game for yourself, because your experience could be much different from mine depending on your standards.