Just had a chance to see this, the show is awful IMO.
The supporting cast are terrible, they all seem too young and implausible as special agents. There were no real Marvel comic characters in this, Marina Hill is about as close as it gets and it's not enough to call this Marvel. The Extremis stuff just reminded me of the awful IM3 movie. The villain was week and totally uninteresting and the conclusion to his story felt like a cop-out, he should've been sent to prison for murder at least. I don't like that they brought Coulson back from death when it was important moment in the Avengers. Maybe he's the movie universe's Vision, but doesn't behave like or have any of Vision's powers so it would be just a waste of a good character like the Vision.
There were some cringe inducing lines in this like "it's an origin story".
And the Snarky banter is just off-putting. I could maybe put up with it from one character but every character spouts the same Snarky quips (as if they all think alike) and especially seems out of character for a leader like Coulson. The editing was also annoying, they cut this show too quickly.
There was some redeeming things about it. I like Clark Gregg and he did an okay job with the script he was given. Ming Na did a fairly decent job and the only other regular I like. It was also great to see Cobie Smulders come back as Maria Hill, too bad she's not a regular. Their mobile command base was pretty awesome (Still why no Hellicarrier?), the action scenes were good, and I like that they brought in Nick Fury's flying car, just wish Nick was there driving it.
I'll try and watch a few more episodes and hope it gets better. If Apocalypse shows up and kills off the supporting cast and bathes in their blood a few episodes later would be a huge improvement.