My original fear was Agents of S.H.I.E.L.D. was going to be Heroes with a Marvel logo on it. While they do share a key element: superheroes living secret lives amongst regular people, the most interesting aspect of ABC's show is that it follows normal, albeit highly intelligent/trained agents, hunting down, saving, or stopping superheroes. There's also a technological flair and espionage-driven story inherit in this fictional universe, and I don't feel every episode will have to focus on superhuman feats, shifting to plots about rival secret agencies and the characters within them.
As a huge fan of Marvel I was hooked with the opening shot, because that particular scene, a kid looking into the window of a toy store filled with action figures of Iron Man, Hulk, Thor, and Captain America, demonstrated to me the potential of the show. In the pilot, there were already crossovers and nods to Iron Man 3 (the pilot's antagonist is infected with the Extremis virus) and Avengers. I suspect each episode will continue in this fashion, possibly containing Easter eggs. The show even has the capacity to introduce new villains, new heroes, new side characters, and new plots that may or may not spill into the movies, as well as leave the door open for major cameos or the development of other characters, something they delved into by recasting Cobie Smulders as Maria Hill. I, like most Marvel fans, am hoping a major star such as Chris Evans or Samuel L. Jackson makes an appearance. It's a small possibility; it would take a lot of convincing and probably a lot of money, yet there's a chance.
The show's longevity is not dependent on A list actors doing cameos. They have Clark Gregg, and he's fun to watch. I have liked the Agent Coulson character since the first Thor movie and his lines, "It's not easy to do what you did. You made my men look like a bunch of minimum wage mall cops. That's hurtful." Gregg has a unique charm in his delivery, and it's entertaining even when the show ripped a scene from Back to the Future. I half expected for Coulson to say, "Where we're going we don't need roads," when the pilot ended with a flying car zooming at the camera. Despite his many appearances, Coulson is still a mystery. He has had little to no backstory, and the show can explore his origins.
I hope I'm not ruining this for anyone that enjoys the show yet has never really been into Marvel comics or video games, but I'm 99.9% positive (POTENTIAL SPOILER) Coulson is a LMD, which stands for Life Model Decoy. For those that don't know, S.H.I.E.L.D. is infamous for employing LMDs, particularly Nick Fury. It's an android double of a person that can be used to hear or see and can also be controlled by the owner--my theory is that the writers might make it more of a clone than a robot, because if it was being controlled by the real Coulson the other agents obviously wouldn't have to lie to it and make up a story about vacationing in Tahiti.
One of the biggest distractions I had throughout the show (other than Chloe Bennett's hotness) was the science duo of Leo and Jemma. They had cool gadgets, brought up interesting ideas, but I missed half of their dialogue due to repeatedly talking over one another. I had the sense they were trying to go for the quirky, fast-paced back and forth and hint of unspoken sexual attraction akin to Tony Stark and Pepper Potts, but it failed. I was more annoyed than delighted, and half an hour into the show, I rooted for their demise.
The pilot wasn't a flawless start. The show has a few kinks to work through, the biggest being the cast interactions. Some actors brought their best while others seemed to still be in the process of finding their groove. There were awkward moments and lines that didn't quite feel right to me, jokes and a few scenes that ultimately flopped (the interrogation room with the truth serum, for instance). I've read a few reviews from other Marvel fans that somehow expected Agents of S.H.I.E.L.D. to have the action of a blockbuster. Please, don't expect that. This is television, where the CGI isn't as advanced (this show probably has better CGI than most other shows), and the budget isn't as grand as a fully produced, 200 million dollar+ movie. If given enough time to develop, Agents of S.H.I.E.L.D. has all the makings of becoming a stellar show, finely tuned for hardcore Marvel fans and the average viewer alike. It just needs a little tweaking.