I think the remaster will be good but probably not worth the €60 unless you're a big SMT nut. I pre-ordered the second I saw the Steam page go up, though.
From what we've heard from the Japanese fans the game has some odd performance problems, like there can be a bit of a delay even just bringing up the pause menu. The Fiend boss battles had some FPS dips too, with the Switch version being affected worse than the PS4 version.
Initially, the game also didn't have the skill inheritance feature we see in P4G and P5 - this meant when fusing demons it was pretty much random what skills would be inherited, and there was a lot of backing out of menus and going back in to them in the hopes you'd get the skill you want. Fortunately, I believe that feature has been patched in, so it should be ready to go for the Steam release.
I think in a couple of months, assuming Atlus keep patching the game, it will definitely be a worthwhile buy and perhaps the definitive edition (if only for the skill inheritance).
SMT3 Nocturne overall is a great game though and one I'd recommend, the Persona composer did the soundtrack and is a perfect example of how flexible a composer he is, it's all dark ambient rather than the citypop jazz we hear in the Persona games.
It's not super heavy with it's narrative, so I wouldn't expect 20 minute+ cutscenes like in Persona. This all kinda lends to it being super atmospheric though, the little interactions you have with people truly do make it feel like you're on your own in the middle of an apocalypse.
Also be warned, this is one of those games that can at times be kinda bad at explaining where you should go. Near the beginning you have to talk to a demon in Ikebukero, but he wasn't there before this point and there's no indication he'll be there now or that you have to go back there, so it's easy to miss... don't feel bad if you have to look things up.