The... boss fights aren't just larger damage sponges. There are (sorta', none of them are actually "just" damage sponges save maybe the golem) a few bigger enemies with heftier tank to 'em, but they're not the bosses. Unless I've already forgotten, there's two proper bosses (the lich fairly easy to get to and not that rough difficulty wise, the magitek angel a bit more involved) and then a pretty nasty (for me, anyway) end-game victory scenario (the shadow/tar/whatever it is siege).
Specialization wise, there's not a huge amount -- the game's indeed fairly small as these things go -- but there is some in the way of relic upgrading and choosing how you go up the tech tree. Base difficulty indeed isn't that complicated, though. I enjoyed it more on the aesthetic front than most things, I think. Gameplay wasn't even remotely "stale" to me, though. I spent most of the time running around pretty frantically and I still got beat fairly hard as the starting character (second felt easier in a lot of ways, but it also ramped up difficulty a good bit faster). Was fun on that front, more or less.
Combat orders are also like... two button presses, iirc. On the keyboard, anyway. Not as obvious as they probably could be -- it took me a few games before I started using them much -- but they quite easily accessible. Consumable icons were all pretty identifiable to me, too. Only ones that approached same-y were the little healy gem things, and they were still pretty distinct. Building categories could be a thing but I'unno if they're particularly
necessary with how many buildings there are. UI's not super great, basically, but I think it's more serviceable than you're giving it credit for. I've certainly ran into much, much worse, so maybe its just my expectations are even lower than yours
