I do feel as if the writer of the Marshall class was more concerned for balanced than many of the other writers were. (no judgement here, I can see the value in power fantasies as well as balance)
However I am currently playing a Marshal in a campaign with a (quite well optimised) rogue and a barbarian and I definitely do not feel underpowered. Allowing the rogue (which is generally balanced for having only attack per round) to attack another time feels very powerful indeed. But granted in an average party he probably gets less power than other classes. Although a thorough read of his level 5 feature does seem to allow you to grant an attack and a maneuver simultaneously, this gives attack and utility at once. Even better at level 10 you can use any maneuver you know with this. I havent fully explored this yet since I've only recently gotten to level 5 but this sounds very powerful especially since some maneuvers allow the user to attack their full amount of attacks. Now I'm not sure if this is rules as intended but it seems to be that RAW that means you can allow an ally to attack AND use a maneuver that allows them to use their full amount of attacks.
Combat directives wording that I base that assumption on:
"In addition, when a creature uses your Commanding Presence to make an attack, it can simultaneously use one Sanguine Knot combat maneuver that you know."
Keywords being "in addition" and "simultaneously".
(the level 10 feat changes the sanguine knot requirement to include any maneuver that you know, with martial scholar or a level in fighter your choice is quite broad)
An oddity that I find is that the marshal can not normally take maneuvers from the adamant mountain school since that is the one that most aids tanks and Marshal seems like a good supporting, tanking class.
However that is easily fixed by taking the martial scholar feat, now you will perhaps say "but my ASI!!" however Marshall does not really have a main stat: charisma, yeah nice for flavour but is actually only used in your level 14 and level 20 skills. Other than that a primary attack skill is nice, but not required, if you are not good at attacking yourself, just let your allies do it. So taking a feat instead of an ASI becomes very tempting.
BTW if you want to minmax the marshal, go with gambling general probably, Talented tactician is nice but kind of overkill since you already get to hand out attack bonuses with mark foe (level 3). I've chosen Talented tactician and while it feels pretty good to be able to give bonuses to attack from 2 sources it kind of becomes overkill a lot of the time. Better to exchange some of that accuracy for damage.
(also Talented Tactician, Swift Strategist, Gambling General, nice alliteration there Mike Myler, which is also alliteration, are you an avid alliteration appreciator?)