I see this just left Early Access. There are a ton of EA reviews saying that this wasn't ready. I'm curious - now that it's fully released, did those kinks get worked out?

I generally don't go through the effort of returning games once I buy them (I also frequently don't have time to even play within the 30-day window anyway... I buy them on sale and then install when I can). This looks like a fun idea, but I just want to know if the game reached a truly final release level of maturity, or if the developer reached a point where they ran out of schedule/budget and shipped what they had.

Thanks in advance.

From what I've read on their Discord, they didn't run out of fumes or funds, with the game selling well enough in EA and Coffee Stain being a solid publisher who's been behind them the whole way. The release of v1.0 simply gets them more exposure which leads to sales so they can continue creating content for the game with people have the comfort of a full release. So, there was no push-it-out-the-door date... if there was, that would've been their initial projection of a 2022 release date.
They've spent a lot of time balancing the gameplay and difficulty, using the feedback from the Discord community. Plus, even though Barya was already playable in the skirmishes, PvP, etc., the completion of the final single-player campaign seemed a logical time for full release.They've mentioned that they're going to be releasing a new roadmap for further additions sometime soon (among other things, it's strongly hinted at that there will be at least two more factions.) There's a lot of lore and images in the game's stories and artwork that don't currently appear in the game, and even now there's room to expound upon what's already there, so I'll be curious to see how far they go with the world.
Honestly, they seem dedicated to the game, and being a Strategy/TBS/HoMM fan, I love that.
As for maturity, I've been happily dumping hundreds of hours into it for quite a few months now, so it's fully playable, just don't go in expecting King's Bounty or Heroes or any other games that may have inspired it; it is its own thing. :)