I've still only dipped my toe in its waters, but I can tell you it's got a solid character creator.
Beyond that, it feels slanted more towards building than Stardew's farming, where building was generally more a means to help facilitate the farm stuff. But for all I know you can grow crops and raise animals to your heart's content in Portia and I'm just not there yet.
Visually, it's got some very pleasant use of colour and everything has a vague Breath of the Wild blend to it which I'm a big fan of - at least outdoors.
Indoor environments break that for me. Most everything inside feels barren compared to the exteriors, and worse, overscaled for camera positioning, much like an old MMO. Super high ceilings, low detail objects. Cavernous. I hate that.
Characters look mostly fine, with a few standing out as maybe too cartoony, but not necessarily inconsistent with the others, at least. A lot of the buildings in town follow that. Cartoon architecture. It's definitely not my prefered look, but whatever.
It plays well, for what little bit of the actual gameplay I got into. Good on gamepad, good on mouse/keyboard. Both are active simultaneously like Stardew, so you can switch to a mouse for precision when you really need it. I find that helps a lot in games like these.
I'll have to get deeper in to say with any certainty but the thought that always enters my head when I'm playing Portia and Stardew is that if you got into Harvest Moon on the SNES, you might prefer Stardew, while if you got into Harvest Moon on the N64 or PS2, you might be more into Portia.