Here's a short overview of the graphics style and technology used in some of the existing cPRG's that are often mentioned on the forum, followed by what we know (or can assume) so far about what Project Eternity will use.
Maybe this can help clear up some confusion...
BG, BG2, IWD, IWD2, PS:T, Fallout, ToEE, ...
camera:
projection/viewpoint: isometric (diagonal top-down)
rotating: no
zooming: no
graphics:
background (terrain/structures): 2D images (pre-rendered from high-quality 3D, and retouched by hand)
animated objects (fountains/machines/...): 2D animations (pre-rendered "flipbooks")
environmental effects (light & shadows, rain, ...): 2D effects (using various tricks like blending pre-rendered light-maps)
spells: 2D animations (pre-rendered "flipbooks")
characters: 2D animations (pre-rendered "flipbooks")
NWN, DA:O, KotOR, ME, Fallout:NV, ...
camera:
projection/viewpoint: perspective (one or more of: first-person, follow, diagonal top-down, manual, ...)
rotating: yes
zooming: yes
graphics:
everything: 3D terrain & models & animations/effects (real-time rendered on the user's graphics card)
Project Eternity
camera:
projection/viewpoint: isometric (diagonal top-down)
rotating: no
zooming: ?
graphics:
background (terrain/structures): 2D images (pre-rendered from high-quality 3D, and retouched by hand)
animated objects (fountains/machines/...): 2D (pre-rendered "flipbooks") and/or 3D animations (case-by-case decision)
environmental effects (light & shadows, rain, ...): 3D effects (blended together with the 2D graphics)
spells: 3D animations/effects
characters: 3D models
Note that this is merely based on what I have heard so far from developer posts & interviews, so no warranty on the correctness of the above information. If you see a mistake or have something to add, post a reply.
A comment from one of the developers, as to whether I interpreted their statements correctly, would of course be appreciated as well.