Alright. I've now had ~3 hours with the game:
Combat is... weird. I suspect it is broken, but every PB game is quite challenging for the first 5-10 hours until you get the hang of things and things also change a lot when you start to get riposte, etc, so I'm not sure. The main difference you experience is that all the animations have been slowed down.The general effect to a PB veteran is that things are a lot slower, though because you are also slower it is not necessarily easier. There are also a couple of oddities: (1) when you are successfully smashing an enemy, while that animation is going on you cannot be interrupted by another enemy. so if you get a combo going on one enemy they sort of wait around. this was sort of the case in previous games too, but it is now more noticeable due to slower animations. (2) the slow animations encourage you to use roll a lot, kind of like in TW1/2; but because typical PB controls mean it's not easy to precisely position yourself instantly after a roll, you're using it mostly for defensive purposes, not offensive. (3) the big problem is the wonky animations. when you do a 'lunging' attack or a power attack, it seems that sometimes you will 'stretch' a bit further (the leap that is already part of the animation leaps a bit further) to hit the enemy - which makes calculating your defense a bit harder. moreover, in power attacks there seems to be a slight slow-down during the middle of the animation, which makes it easier to dodge them with a roll. The end result of all this is that with some enemies, like giant crabs, I figure out that I can power attack at specific intervals and just roll over them, while with others (mainly leaping ones like claw monkeys) it's easy to die in a couple of hits. In short: the mechanics have changed oddly and I suspect for the worse, but I need to play a bit more to say for sure given how PB combats work.
World Design / Quests is basically R2's small islands, but with the improvement that all the islands open up immediately after the tutorial. Sadly, I think PB really were broke when they made this thing. You visit several old locations like Tacarigua and Antigua, and the theme is that shadow creatures are coming out the wazoo of the earth and everything is going to hell - so you visit the vibrant town of Antigua that was full of NPCs and gave you enough quests for hours of play in R2, and it's basically a ghost town now. I haven't visited all the islands, so it remains to be seen whether this is a shell of a game that will be over quickly or the NPCs and quests have been distributed across the other islands. It sure looks like a prettier version of R2 though, which at least is a good thing.
Story/Writing - well that was mostly nothing to write home about in any PB game, and the central European charm of G1/2 of course was always going to be gone with the pirate theme. I actually like the pirate theme. Somewhat like D:OS, the main story bits I've gotten so far are amazingly stupid, and the opening cutscenes are proper C-grade facepalm, but normal dialogue has actually gotten a bit funnier, with the protagonist telling every NPC how stupid they are. The protagonist voiceover is something else, though. Basically some drunk skinhead with a lisp who listens to Nickelback.
Basically, what I've seen suggests another Risen 2, though much depends on how it pans out over the course of the game. Risen 2 actually had many little bits that were fun, but suffered from an inability to appropriately pace and balance various gameplay elements and tune the combat. I think at worst this will turn out to be similarly flawed as R2 but shorter, which would be a sad predicament for PB, and at best, it could turn out to be some sort of R2+ that is basically R2 but manages to offer a better paced game in terms of combat and quests. (Yeah, I'm being hopeful.)
In short, if you thought R2 was good for what it is / fun enough, then this will turn out OK and possibly good - if you thought R2 was an unplayable abomination, probably don't bother. I don't know how anyone could say this is a 'return to the roots'. But having enjoyed R2 while simultaneously being disappointed in it, I'm also feeling the same with R3, and will play on for now.