I would like to preface this bit of feedback with am important caveat: I am mostly negative on SF2e as a concept. That might (and probably will) color my view of the Field Test going forward. That said, I did playtest this with a few friends at a private table. These are the things I felt during playtesting and reading through the alloted material.
The TL;DR is that a lot of the soldier seems confused: it's a specialist that uses things that, in general, don't require much specialization to be good. The feats and subclasses are either math fixers (not very exciting) or just clash against the class' vibe. Unfortunately, it's previous niche (weapon attacker) is already taken by the Fighter.
1)Primary Target, as written, doesn’t fit the whole schtick of the class: if the point of the soldier is to use their big Class DC instead of their attack role, why have a feature that explicitly uses their attack roll and make it easier to miss? If I hit with the attack roll, do they still need to make their save vs the damage? If so, do they take damage twice?
2)Bombard's feature should be a part of the class without being a subclass, at maybe a higher level. Suppressing targets seems to be the core of the Soldier’s playstyle, and making a feature that pushes them to be the best at it above all others optional seems counterintuitive. We’ll have to see more of the class’s features before this can be solidified, however.
3)Close Quarters feels fundamentally out of place. You're giving up the main idea of the class (big area weapons) in favour of being a Champion with less support for Champion-like abilities. Feels like an identity crisis of wanting to keep the old close quarters fighting styles.
4)Fearsome Bulwark is a great feature. Helps make the soldier less dead-weight out of combat by giving Con a skill utility.
5) Feats require more playtesting, but Steady Up doesnothing except make you harder to move, since an area attack is 2 actions and this is 1 action to make only your next attack 1 action, so it’s still a net 2 actions. Maybe make *all* your Area Attacks 1 action until the start of the next turn, to really sell that “Living Turret” fantasy? At the same time, most Automatic weapons are Unwieldy, so even that wouldn't fit
6)Reloading and Capacity need to be cleared up a little bit: after looking more into it, it’s clear how it’s supposed to work, but it’s confusing to have weapons be “Repeating without being Repeating” and having “Capacity that isn’t Capacity”. Might be a detriment for the system in general, and I think this is the flimsiest piece of feedback I have
7)Bringing Unwieldy to 2e opens up an interesting design space in PF2e, where from experience big single attacks are discouraged by the math. Making Unwieldy weapons have advantages over normal big weapons (like Greatswords and Greataxes, for example) can push people to use stuff like Power Attack more, which I’m all for. Still, it needs support, but I’m excited to see what happens with this trait.
I am not a Gm, so I can't comment much on the Monster side of things, but nothing jumped at me that seemed wonky.