For the most part, I really enjoyed the pilot. There is action, intrigue, a faceless villain of unknown power (which will no doubt provide a long story arc-- most likely over the entire season, if not more) and decent characters. I liked the two fast-talking techies, Fitz and Simmons, and I liked the setup, the way that they referred to previous in-world events (i.e. "The Avengers"), and I also liked how the first "hero" that S.H.I.E.L.D. chases down does not have powers without any explanation. I was worried they weren't going to give us an explanation for his increased strength, so I was relieved that they used that as the beginning of the unseen baddie mystery.
The characters are likeable, the action was fast-paced and the special effects are high-budget enough to be believable. And, of course, there was humor peppered throughout the script. It just wouldn't be Whedon without humor.
And it just wouldn't be S.H.I.E.L.D. without Agent Coulson. I was extremely worried about his resurrection story, and though they didn't give any real explanation for it, they used it to set up yet another arcing mystery. Coulson was a highlight of the last few Marvel films, in my opinion, and though I was upset that he was killed in "The Avengers", I still worried that bringing him back to life would prove to be a bad move. After his hilarious entrance in "Agents", though, I'm not worried anymore. I just love the guy.
The only thing I really didn't like was at the very end of the episode. It was a "Back to the Future"-ish visual gag, and it struck me as unoriginal. Maybe it was meant as an homage, but it felt silly and out of place.
I don't want to give any spoilers, so I'll wrap up this mini-review with a recommendation. If you liked the last batch of Marvel hero movies, and especially if you liked "The Avengers", you will probably like "Agents of S.H.I.E.L.D." It's probably not for everyone, but I do think most people will enjoy it. I was thrilled to have a show the entire family could sit together and watch-- I hope that remains the case. I also hope the show does well enough to really have a chance to stretch and grow and develop. The potential is enormous.
Long-time Whedon fans know what to expect from him: witty dialogue, subtle humor, long-range storytelling, visual, verbal and literary surprises and loveable characters. (Oh, and the killing off of favorite characters from time to time.) From "Firefly" to "Buffy the Vampire Slayer", Whedon has a built-in fanbase-- not all of whom are nerds or geeks. Whether that fanbase is large enough to support "Agents" will remain to be seen.
Also, when Whedon begins production on "Avengers 2" (or whatever it's being called), and other projects, he will be less hands-on involved in "Agents", so it will remain to be seen whether the show will be as good without his direct involvement with every episode. I certainly hope he doesn't end up too distanced from the day-to-day action. He is what will make this show great.
Now, for your entertainment, a little Phil Coulson in action: