I finally got to see this, and I really enjoyed it. There may be spoilers in my following words, so there's my caution if you haven't seen it.
As others have said, its biggest downside is that its plot points don't seemingly (viz. apparently) coalesce to anything of much substance. For the most part, I enjoyed the gags and paranoid conspiracy points, though my two biggest gripes are that (1) they didn't seem to readily add up to much of meaning or didn't really get me thinking about anything too important right away (i.e., something of substance), and (2) that some of those plot points were just a bit too campy. Inherent Vice is weighted with convolution and confusing threads that may or may not be plausible but that lie just beyond our total comprehension, suggesting some secret world, something sinister, something serious that we're either just not noticing or are even being actively diverted from noticing. On the other hand, it's sort of the opposite in Silver Lake: Andrew Garfield wants to find something of meaning, wants to have some revelatory experience, but instead just travels through the weirdness of LA mythos, pop culture, and the vapid, vein pursuits of LA oddballs and rich people. So maybe that's where the meaning lies. However, the connections of the conspiracy are too goofy and too unbelievable to be treated with the pressing importance that, say, a Pynchon novel or the Inherent Vice movie might have.
Still, I really enjoyed this as I said. Consider that I watched The Nice Guys starring Ryan Gosling and Russell Crowe the night before, a movie that sports 92% on Rotten Tomatoes and 70% on metacritic (both better ratings than what Silver Lake sports on the same sites). Where these movies relate are that they're both sort of LA noirs/detective stories, albeit The Nice Guys is a buddy-cop movie. Still, I would argue that The Nice Guys is COMPLETE fluff. The cinematography in The Nice Guys is competent and very well-done, but lacks the artistry of the cinematography in Silver Lake (more on that later). The script for TNG is far more generic than the script UTSL. The music in UTSL is less generic, fits the story more, is more noticeable, and so on. Perhaps it's an unfair comparison because they're really for different audiences despite being somewhat similar, but my point is that although UTSL lacks some substance, it's not nearly as much as a run-of-the-mill comedy for the masses.
Where UTSL does totally shine without question is in the cinematography. As I mentioned in my original post, I was excited for Mike Gioulakis, and he did a fantastic job here. The slow zooms, wide-angle portraits, night scenes, etc., all fit the mood so well from scene-to-scene and become part of the story by helping to convey what Andrew Garfield is experiencing. Seriously, everything from lens choices to the way he lights rooms and outdoor night scenes is fantastic. There's a lot of artistry here and I'm confident in saying that Gioulakis is one of my favourite DPs; I think he may be my favourite cinematographer for lighting night scenes (he did it so well in It Follows and does it again here).
The last thing that I should mention about the movie was that it was a lot of fun. Sure, the plot wasn't perhaps as engrossing as it could've been, but I was still engaged. Just bathing in the LA mythos and visuals is enough. The one qualifier is that I'm younger and probably not as much a seasoned cinephile as others here, and I prefer to watch movies that will appeal to my tastes and biases, rather than consuming in quantity -- so I can't really speak to the idea of fanboy cinema here.
To some of the posters above, keep in mind that Inherent Vice is a lot of talking and still cameras/very slow push-ins across a pretty long runtime, so I totally get why lots of people would be bored. As a PTA fan and Pynchon devotee, I even thought that PTA could've used more steadicam and less cameras just focusing on actors talking. Yeah, PTA has said that what he finds most interesting in movies is actors doing their thing, which means focusing on them in conversation, but that's his biggest downfall to me. Anyway, my point is that I can totally understand why someone would find IV boring or get bored after an hour and a half or so.
