At this point, there are probably three types of AGENTS OF S.H.I.E.L.D fans (with significant crossover, of course):
1. Marvel Cinematic Universe completists watching to make absolutely sure that they don't miss any subplots, threads, etc being either launched or tied-up here.
2. Fans of all things Marvel and/or comics in general watching to make sure they don't miss appearances by any characters or iconography that hasn't shown up elsewhere yet.
3. People who've genuinely become invested in the characters/world of this specific show, care about the characters and want to know what happens to them.
"4,722 HOURS" is a rare episode that feels designed with Audience #3 exclusively in mind: It's a single story strictly involving the series' own storylines, no cutaways to any other subplots and no (definitive, at least for now) ties to either the Cinematic or Comics Universe. It also happened to be pretty damn well-executed and a fine acting showcase for Elizabeth Henstridge, which I imagine helped soothe the lack of case-specific goodies for viewers of other stripes.
For those just jumping onboard: Midway through Season 2's back-half, it was discovered that S.H.I.E.L.D has been in (high-level secret) possession of a mysterious stone monolith that morphs into a "living" liquid form and back again seemingly at random and has existed on Earth since ancient times. In the final moments of the season finale, said monolith managed to leak out of it's containment-cell long enough to liquefy and (apparently) swallow Agent Jemma Simmons whole. Earlier this season, it was discovered that the monolith actually functions as a time-space portal and that Simmons was still alive... but had been zapped off to a mysterious alien planet that looks absolutely nothing like the California desert processed through a blue day-for-night filter.
Through the obsessive dedication to her rescue of her BFF-who'd-really-really-really-like-to-be-more Agent Fitz, Simmons was rescued and yanked back to Earth early on but has demonstrated signs of detachment and strange behavior ever since - particularly in a resistance to picking up her awkward mutual courtship with Fitz where it left off (he had just finished managing to ask her out to a for-real romantic dinner when the monolith "ate" her.) This culminated in a stinger from two episodes ago, wherein she confided in fellow Agent Bobbi "Mockingbird" Morse that the real issue she was having was that she was desperate to get back to wherever it was she'd been marooned. "4,722 HOURS" presents Simmons' story of her ordeal as she relates it to Fitz (who's help she requires to "go back"), in order to explain not only where she was and why she'd want to return... but why she was so reluctant to tell him in the first place.
The fact that there weren't many other reasons for her to keep a secret from her best (only?) lifelong friend that made any sense, it would appear that most fans already figured that last part (she met and fell into a romantic relationship with someone else while offworld) out well beforehand. But even with the guessing games neutralized, the meat of the story (NASA sent an astronaut team through the portal 14 years ago, Simmons is rescued and ultimately falls in love with the last survivor of the doomed expedition, Will Daniels) was compelling and interesting; even as the "showcase" stuff re: Simmons showing off her DIY survivalist chops before meeting Will was frontloaded into the beginning.
Budgetary issues for non-recurring FX, sets, etc is AGENTS OF S.H.I.E.L.D's consistent bugbear, and while there's a certain amount of charm in the oldschool B-movie solutions this episode pulls out to try and work around it (I almost wish they'd gone all the way and just openly shot in Bronson Canyon - or did they?) it's hard not to wish that the alien world looked a little more "alien" or that there was more creature-feature action than Henstridge (however enthusiastically) pretending to wrestle a floppy rubber tentacle we're meant to imagine is attached to some much larger water-monster. Still, if they were saving the money for their big "mystery heavy" (the planet is "haunted" by a shadowy shape-shifter who comes and goes with the aid of a powerful sandstorm) it was probably worth it, as those sequences were impressively "different" for the series.
On the other hand, much as I enjoyed this one, I'm worried about where it's going. Fitz's luckless longing for his platonic lifemate has been at the core of his carefully-managed "adorkable" persona from the beginning of the show, it's been fun to watch AGENTS prod at it for drama to make him even more likable/identifiable (he has now endured drowning, shootouts with terrorists and diving into a black hole for this woman, but - awww! - still stammers like a schoolboy when actually trying to ask her out) and it's very in-character for him to immediately decide to help her rescue Will is perfectly in-character... but I hope they don't take this too far in the obvious direction.
Yeah, it's hard not to feel the character (he risked his life multiple times over to save her and it turns out she met someone else? Ouch!), but "Woe is me! Even the female nerds I actually have things in common with prefer jocks!" (it's made expressly clear that Will isn't a scientist, he was the other astronauts' macho survivalist backup) is a really tiresome male nerd angst trope, and I'd really hate to see Fitz become an icon to the internet MRA "male geeks are denied the sex we're entitled to!" set because the show decides to give him one righteous feeling-sorry-for-himself monologue too many over this. (By the same token, I'm genuinely depressed imagining how much slut-shaming hatemail and forum-posting is being directed at Henstridge right now.)
- Yes, when Will said that the planet "has moods," my first thought was Ego: The Living Planet, too.
- I'll say it but I bet I'm not the only one thinking it: How cool would it have been if "Will Daniels" had been John Jameson III instead? It's unlikely, but I wonder if that was ever floated as a possibility - he's never been among the most important tertiary Marvel characters (so he's probably not a big part of anyone's movie plans) and it'd be quite a "we're still worth paying attention to!" coup for AGENTS OF S.H.I.E.L.D to have debuted the first official piece of the MCU-official SPIDER-MAN world.
- If AGENTS does one thing consistently, it's nesting reveals and twists inside one another in multiple layers. As such, it's probably safe to say that there's more to Will than we already know. The fact that we only "know" that his crewmates went space-mad and had to be killed in self-defense from his story (Simmons finds the bodies of transportees from other eras, but not them) his very science-ish understanding of the planet's glowing-hot substrata, etc. I hope he's not an out-and-out villain, as that would play way too much toward the "Lament of The Nice Guy" stuff I'm hoping they avoid re: Fitz.
- That said, if Will IS a villain, a possibility would be that he's actually just a further manifestation of whatever the Big Evil on the planet is (see below) and all his actions have been to trick Simmons into pulling him/it onto Earth. (Alternate theory: He's a Skrull.)
- On the other hand, y'know what we've been hearing a lot lately? "Death," used in atypical contexts. The Hebrew symbol for the word was on the scroll Fitz found that helped unlock what the monolith was, and Will refers to the Big Evil in the sandstorm as a personification of Death. As readers of these recaps are likely already aware, Death Personified is a major Cosmic Marvel figure whose romantic attention is the motivating goal of INFINITY WAR's big central villain. So, there's that.
- On the other hand, if Death is going to be an MCU character (I still think it's more likely they'll conflate Death and Hela into one character, debuting in either DOCTOR STRANGE, THOR: RAGNAROK or both) I can't really imagine AGENTS getting to be the place where she first appears. More likely, though, I think the whole monolith/portal/weird-planet subplot will tie back into the Inhumans/Kree business that's still technically the "A-plot" of Season 3.
"AMONG US HIDE..." is mainly promising more of the "Let's Get Ward!" storyline (yawn) but with Bobbi finally getting back into the field (yay!) for what may or may not still be a build towards the spin-off. The teaser is being explicit calling Andrew dead, but I don't care - I'm still thinking he's Lash. The title, incidentally, is a reference to Fantastic Four Issue #45, which featured the debut of the original Inhumans Royal Family; so presumably there'll be more from that storyline as well.
ALSO: We're still awaiting the appearance of Powers Boothe, who's scheduled to reprise his role as the (now former) Security Council head from AVENGERS and WINTER SOLDIER. Word is AGENTS OF S.H.I.E.L.D will reveal his character name if Gideon Malick, which some fans are predicting is a clue that he'll be the MCU version of Albert Malik, aka Red Skull II.