My comparison to the first Grandia was about how both games are largely driven by the character dialog, not about the specific combat mechanics.
To me, Trails combat is pretty unremarkable. That's not necessarily a bad thing. It's competent enough that it doesn't get in the way of the storytelling - unlike the combat in Xenosaga Ep. 1, which we are now comparing it to. But if you try to stack its combat up against some recent RPGs like Divinity, Bravely Default, or Ys, I don't think it can really compete. The combat in those games is what keeps you coming back for more. The combat in Trails is good enough to serve its purpose in the game, but it does not steal the show.
I would agree with that assessment entirely, yeah. But remember, this is a game from 10 years ago, so it didn't have a lot of these modern titles to contend with at the time. Sen no Kiseki is the modern Kiseki game, and the battle system there is far improved -- it takes what worked in Sora no Kiseki and iterates upon it, crafting something a lot faster and more streamlined but with more options built in and more variety. Falcom essentially took Sora no Kiseki, sped it up, added multi-character combo attacks a la Chrono Trigger, the ability to attack enemies on the map to stun them in order to get a greater advantage in battle a la Xenosaga (once again), the ability to auto-win easy battles a la Earthbound, and threw in a bunch more original options for good measure.
So if you're playing Sora no Kiseki, you're seeing the start of something really cool -- the first attempt at a brand new battle system for the Legend of Heroes series (which had more or less been using an RTS-style battle system for over 10 years at that point) that would later be changed and improved upon with each installment, much as every new Ys engine is changed and improved upon with every new installment that utilizes it.
That is the Falcom way. And it's part of what makes them such an amazing developer.
...My point is, if you play Trails for the first time, do bear in mind that you're playing a 10-year-old game with what was at the time a brand new, entirely untested battle system, so you're not going to get absolute perfection right off the bat. But if you appreciate it for what it is, it's actually pretty impressive, and shows how much of a chance Falcom was willing to take with the newest entry in what was then their secondary flagship series (and is now unquestionably their main flagship).
-Tom