tl;dr: The game is still missing a ton of volumetric lighting effects that were in the original release, and those that are there are much more subtle. Yes, this is post-patch.
Let me start this by saying that, if you have never played metro 2033, whether it be this version or the original you should get it.
(All comments are after the first patch... which seems to have variety of missing effects. Not sure how that happenned)
Now specifically to this version... while from a technical and performance perspective, this definitely is an improvement over the original, I feel that some of the artistic changes made during the transition hurts the mood of the game, and is an obvious downgrade in the overall atmosphere.
This is mostly obvious at the major events in the stories, in which god rays were either toned down (such as in the intro, where the godrays are a more subtle effect with an additional, and very strange, red streak that won't leave the screen) or totally eliminated.
Godrays aside, there are still some more subtle changes in the color and over all tone of the game that shifts it from more of a moody/horror feel to a more actiony one, though so far this hasn't been too big of an issue.
Besides that, as far as gameplay goes, its still Metro, though now you can customize your guns instead of having to buy 'premade' combos, which is a very welcome addition to 2033. Gunplay, AI, etc. seems no different. Its 2033 with a new coat of paint pretty much.
Overall, if you have 2033, don't buy it. 2033 is definitely showing its age at times in game, but it still is damn fine looking at times. If you don't have 2033, then as I said before- sure, this is a fine starting point, though honestly you'd be just as good buying the original.
On a side note, the graphical options are still just as awful as ever. There is a general quality option, a tesselation option, and motion blur option. For AA, you can do super sampling in game, though no other AA method is offered (however, the image is clearly anti-aliased, so there is some post process AA going on).