It's pretty horrible!
Resident Evil, to me, has always been an experience for a full screen, a dark room, and the sound turned waaaay up. And I know there have been portable REs in the past with varying results (I'm lookin' to you, Resident Evil Gaiden), but they haven't garnered much attention for quality… the previous 3DS entry gained more attention for the lack of ability to initialize data so people couldn't sell it back to places like GameStop. I don't know if the data system will have the same issue, but the game itself is shaping up well enough.
The demo I was able to get my hands on featured Jill Valentine maneuvering through the residential quarters of some kind of ship, and while it was short it felt complete. The over-the-shoulder view blocks a bit too much of the left side of the screen leading to some frustration in fight-or-flight situations, and it was a little slow to get the crosshairs in just the right position (wasting a lot of ammo in the process if you're not precise), but that's Resident Evil. And with a quick options check, that shouldn't be too big an issue come release.
Revelations might well be the prettiest portable game I've ever seen and is complimented well by the 3D effect instead of being a pain to the eye-socket. Jill looked great (still haven't gotten the number of her trainer) and the world surrounding her was finely detailed. Only a handful of rooms were actually available for exploration (and extremely close quarters on top of that), but everything from the bed, to the bookshelves, to the control panels were beautifully rendered. Put it all in 3D and the world simply pops.
There wasn't much fighting in the demo, with only two guns shown and no melee attacking at all (that may be reserved for Chris Redfield), but engaging with the melting baddies was easy enough. Guns can be aimed or fired from the hip, but get used to the first-person view when fighting or else ammunition can be depleted super-quick… though most of the baddies take bullets with a groan and little more. We'll see just how much they can take in the final incarnation.
With a world that feels finely detailed and realistic (except for the crazy monsters, of course), RE: Revelations is shaping up to be a fun romp wherever you want to take it. It'll be out early next month, so grab the ammo while you can!