I eventually got the game. The combat system is pretty cool, as it "mimics" the series well in giving a lot of options do dispose of low grade opponents (raids/links, aka coordinated attacks, and supports from units in range who haven't acted yet + "greater cleave" for everyone). It all feels very gundamey.
However, the progression is completely bonkers. I started in the highest difficulty setting, and had my squadrons mostly play cheerleaders while the story character guests cleared most of the levels, letting my squadrons feed on some kill, as they would get murdered by any opponent.
So in a way, it really felt like playing the no name pilots in the beginning. But as soon as I could recruit named pilots and main character gundam, it became much easier (a bit too easy actually, with the dispatch missions granting experience from AFKing.).
It is also weird to have the main story characters not under your control (even more so as you need them to complete a good part of the objectives), and your own squadrons never being acknowledged.
So it is a sequence of missions with some summary of the corresponding animes, using named pilots and suits (unless you are a masoschist) from all series (sometimes, you can even will have clones of some of the guest characters in your team), so it feels less like a RPG than most other tactical RPG, and feels closer to an offline gacha game (fire Emblem HEroes, Langrisser Mobile), which is made even more obvious with the AFK dispatch system (you can send some of your units to "grind" and become unavailable for a fixed number of real life hours).
The lack of permadeath is also a disappointment (and reinforces the Gacha feel), given how some of the anime series kill characters left and right.
There's less of a focus on customization of individual mobile suits compared to wanzers. The previous entry had you create squads of five units which were assigned to a transport ship. Some ships could hold 2 squads. You started out with a selection of original characters or you could create your own custom characters. As you progressed in the game, meeting certain goals would let you recruit characters from the various series. Only a few mobile suits are available at the beginning and you gain the ability to manufacture new ones by either capturing them, upgrading an existing suit, combining two different suits, or putting a specific pilot in one. Pilots have several stats and special skills. Mobile suits can be equipped with up to three special parts that modify various stats.
This part hasn't changed, but it is now easier to train whoever you want, or upgrade the mobile suits you want (as the cost to improve them depends on the current stat, and not the imrpovement points spent on the stat as it was before).
Overall, the game is very pleasant, and I find the combat system reinforces its theme(piloting mobile suits feels great here, while it felt frustrating in BattleTech), but at the same time, the "story/pretend" layer is as thin as in a gacha game (but one in which you don't have to spend thousands of hours or dollars to grind).