The new show is a spin-off of the popular Avengers movies, produced by Joss Whedon and starring Clark Gregg as Phil Coulson (the show has yet to explain how Coulson survived what happened in the movie, with some fans speculating he may actually be a LMD).
Pulling off the popularity of the movies and drawing in fans with writing assistance from Stan Lee and Jack Kirby, the show's pilot episode broke records, but a third of the audience vanished after episode one - leading some to speculate that Whedon has failed yet again (He has not managed a truly successful show since Buffy).
Agents of S.H.I.E.L.D. is not Whedon's best work - it's not as good as the doomed shows Firefly and Dollhouse, which were amazing - just not popular enough to survive. Agents is getting better ratings, but how long that will last is unclear.
Whedon did manage to escape his tough female fetish...for about one episode. It's clear that his favorite character by far is Skye (Chloe Bennett). (The other "strong female character," Melinda May, is too much of a Black Widow ripoff to blame Whedon for). As usual, Whedon's female characters are better than his men. The dialogue has the classic Whedon snap (with, no doubt, some influence from Kirby and Lee). However, the show is not as good as Leverage - a more reasonable comparison than any previous comic book shows. Like Leverage, it harks back to the classic 1970s television shows, albeit with more character development and arc between episodes. The team hasn't quite gelled yet, although I don't expect the exceptional chemistry between the cast that so far I've only seen Leverage and the original Star Trek series reach. That's rare and I don't think you can create it, only find it.
The show's good. It's just not great. It's not Dollhouse, which disappoints me (I loved and adored that show). Is it worth watching? Yes. Will it last more than one season? Doubtful.