Finished Edelgard route, overall it's a bit of a nice twist on the usual formula of Empire bad, Alliance good that is way too overused in games. I think I'll take some time before deciding if I'll have a ng+ or not (and if yes then with what house).
I think the removal of the weapon triangle was a big mistake since it removed with it a lot of the strategy involved in battles. The weapon triangle made you always aware of who or what was attacking you so no one was safe and made you balance your group or plan for the map ahead, while in my game (which was on hard) the characters got so obscenely powerful I could just throw them out against multiple attackers and know they'll come back in one piece (and likely kill every attacker). I still felt like magic users were way too op (especially with range enhanching items) but that might be me jewing out on using the rare weapons (while casters have no such limit) and having basically infinite heals makes items pretty pointless and attrition non-existant. Archers felt a bit too weak but that might just be bad rolls (Shamir actually managed to get a zero stat level up once).
Plot wise part 1 was WAY too fucking long and it's really the main issue for me on starting ng+. The persona shit doesn't mesh well with the fact characters can die, so the plot was very limited to only the house leader while the side characters say a line once a month and then disappear into the background. It also doesn't help you don't see any of the politicking involved with the war until it's way too late to get invested. From what I understand Blue Lions actually make the first part more tolerable with actual effects of the main story, but having it limited to a single house is just bad design. Apperantly the different routes makes Rhea/Edelgard go insane to justify them being a villain? This sounds like a very lazy solution rather than have consistent character writing. Also having a third neutral house with what amounts to a "true ending" is a huge cop-out.
Crests were very badly utilized considering they are seen in-universe as a massive thing. They give you a small bonus once in a while and that's about it. Why not make it so only characters with crests can use specific spells (for example, faith magic)? It's a bit overused trope but it makes a hell of a lot more sense. The idea of talents was kinda meh, you are extremely limited by the classes (want a winged archer? Get fucked) and just encourages a ton of meta-gaming (especially if you angle for a specific master class) rather than having freedom in creating different character classes. For example, there is no sane reason not to learn faith and magic at the same time, especially for female characters.
I think the game would have been better by cycling the player character between the houses in the first part (and turning off ally death for it), giving you a lot more emotional stake with both the house leaders and members, and culminating it in a choice of which house to follow in the war (which can be jumped straight into in ng+), massively cutting the tedious start. Afterwards the second part can have ally death and killing characters you used to control will be far more interesting.
And if the devs really wanted a true ending route, it would have been easy to have one where Byleth goes back in time to the end of part 1 and prevents the war alltogether. Have the leaders of the 3 routes join in with their end-game stats and it would have been cathartic.