I beat XCX a while ago now and I realized how broken Ghostwalker is. If you have a setup where you can get a ton of TP to get into Overdrive and reactivate Ghostwalker, you will never die.
I thought the plot was good, but it's not as good as the original's. I might fight some of the super bosses, but that depends on how motivated I am. I need more Miranium and some other stuff to get the Ares 90 to stand a chance.
Ghostfactory is even more broken since it has very short cooldown time so you can keep renewing it especially when the boss can get through your decoys fast. AND it also helps your party members survive (even if they are useless).
The side stories is where the a lot of the interesting stories lie, unlike the original Xenoblade. The original Xenoblade had more run-of-the-mill fetch and kill quests. Not saying that this game doesn't but it often puts a nice story twist on it, with many quests leading to some change in NLA or more backstory, or just a really cool side story. The side quests also have tons of cutscenes since they are more dynamic. Sometimes changing your approach changes the consequences as well even if it is not a direct choose A or B quest (where A is death of a NPC, or B is life). There are also some pretty happy as well as pretty sad quests.
And about the A90. It might be the most powerful skell at BASE level but getting another level 60 Skell and outfitting it with tons of gear with stat boosts, and even more augments can create a much more broken skell. Especially since they can make the overdrive last longer by having more cockpit times due to having 6-8 arts (6 when you have 2 superweps) compared to the 4 unchangeable arts of the A90 of which only 2 are really powerful.
I still have to work on such a skell though when I get back... I am thinking of making a super evasive Formula like that. Although it will break if it gets hit >.<
Or you could just ground gear the bosses haha. Which I have found out is entirely possible (even the ones that normally need a skell) with a good equipment and a decent strategy, along with combat probe support. It obviously depends on overdrive to pump out extreme damage