Have you looked at the player reviews on gamespot.com? The majority are very positive but there are a minority of strongly negative reviews too, which seem to be mostly from fans of the previous games. I have avoided everything but skim-reading reviews though cos I don't want the spoilers, but it would probably be a fairly useful thing for you to read.
I can't speak for fans of the originals but I will say that Oblivion fans will be pleased with this game, as it takes the general game mechanics of Oblivion and tweaks them generally for the better. Don't worry though as it is not the same game as Oblivion, in particular the character interaction is far better. As for voice acting I should say that it neither makes nor breaks a game for me, it could be better in Fallout 3 but I couldn't care less. It is just a minor thing like graphics, I am far more interested in immersion. The game is immersive, you do feel more involved with NPCs, and your actions have consequences to a greater degree than in Oblivion. You can more or less do whatever you want, and I've seen events develop in a different way to how I expected them to.
As far as I can tell you won't be able to complete the game without engaging in some kind of combat, and with that in mind I suppose this is an 'action RPG'. But that does not mean that combat is the alpha and omega of the game - having a strong personality allows you to do things that you could not do if you invested in say, raw power. My personal opinion though is that a game that you could complete most of simply through communication would not be a very fun one; I believe this because you get to select your characters attributes, and you select your dialogue options, meaning that it comes down to pre-selected stats and probability which you can weight considerably. There is a benefit to being good at every aspect of the game and the fun for me is in compromising and adapting to circumstances. For instance I am not sufficiently skilled in repair to fix my equipment beyond a certain point, and I will fix this on my next level-up as it is - I think - my most pressing concern.
The negative things that I have experienced so far are a slightly inefficient interface (this isn't helped by being unfamiliar with the purpose of items), and frequent crashes (which have been reduced by installing new drivers and lowering the graphics). Anything else I could say negatively would be nit-picking. I've only played it one night though, and my opinion will change, but for now it is pretty much what I had expected and hoped for.
