It's RTWP (real time with pause).
It doesn't use turns in the sense D:OS does, it's theoretically much faster (well in practice too) but for harder modes and harder encounters you have to micromanage a LOT - fighters and rogues have stuff to click unlike the old Infinity Engine games.
To be honest, in backer beta, you start at level 4, a bit undergeared, and I found the combat really hard - so much so that I switch to Easy when testing classes.
In short though, if you liked the old IE games (Baldur's Gate, IWD, Planescape Torment), you'll probably love PoE.
It's got a lot of depth, possibility to role-play, deep and complex character development, pretty good artstyle and graphics.
I've been so hyped about Bloodborne, but this might just end up the highlight of the year for me.
Well, there's Witcher 3 too... Good year for RPGs.