Halo 4 is technically impressive with respect to the cutscene animation system, and nearby geometry can be quite dense. Campaign usually maintains pretty good performance in single-player, and the game runs at 720p.
Dynamic lighting, water, skyboxes, geometry LOD, garbage collection, destruction transparencies and physics, and gameplay encounter ambition are all largely downgraded compared with Bungie's efforts. The game lacks motion blur. Between the lack of AO, the questionable HDR, the game's extreme tendency to not draw shadows, and some deficiencies in the static lighting model, objects frequently don't "sit" naturally in their environments, especially when moving between various light levels. There's some low-quality bullshit shadowing on the ground in some areas which is supposed to add detail and "pop" to the scene; it always looks incredibly smeary and/or blotchy (see: Ragnarok). Dynamic objects are frequently very low-quality. Halo 4 also tends to make larger compromises compared to its predecessors for split-screen; Halo has rarely been perfect with split-screen, but Halo 4's looks like total crap
and performs like total crap.
Halo 4 is also incredibly inconsistent. Most of the "in-game" screenshots that people make a big deal out of are vignettes with relatively little going on. A lot of the more ambitious areas try to have the "detail" that other areas do, but wind up looking rather...
spread thin:
Reach looks and feels more impressive and cohesive to me.
I actually think the PS3 version of FF XIII is the most technically impressive looking game of the PS3/360/Wii gen. Upscaling to 1080p with detailed background and monsters, and faces that detailed and expressive, with eyes of full of character and emotion, is no joke. True there was the occasional stutter but most games didn't even bother trying to display at 1080p on that kind of hardware.
Err, what's the big deal about upscaling to 1080p? FFXIII uses a 720p2xMSAA backbuffer. Sure, it "upscales to 1080p" in the sense that the image you see on your 1080p TV has been scaled up to 1080p. But you could say the same about any game you play on a 1080p TV that isn't being letterboxed.
Now, the geometric sampling is nearly 1080p thanks to the MSAA. But that
1-Doesn't mean it resolves with 1080p clarity, and
2-Won't help you with the shader aliasing, texture aliasing, or grainy alpha-rejected transparencies.
As for the level of detail, FFXIII isn't really all that impressive. Some of the skybox textures are reasonably nice, but it's a very low-poly game by seventh-gen standards; character models are typically in the ballpark of only 8000 polys. Which was possibly reasonable given the game's camera, but they're very blocky upon close examination.
The game is
gorgeous, but the actual tech within it is pretty uninteresting.
But that's my most visually spectacular game of the gen. How can the sequels look and run soooo bad!?
In XIII-2's case, the poor performance is due to greater ambition in the design of areas, both in terms of gameplay and graphics. Areas are typically more visually complex, with more complicated visibility; there's more aggressive use of transparencies, and some areas with extreme unavoidable overdraw (like the thick grass of the Steppe). There are often more dynamic objects in play. In places, there are multiple shadow-casting light sources. The game applies a pseudo-DoF effect that doesn't exist in FFXIII.
Lightning Returns is the logical result of trying to make large seamless areas work nicely in that engine (which from what I can tell doesn't seem to even have any texture streaming), while developing on a very low budget per the game's ambitions.