As you know, the first season of Agents of S.H.I.E.L.D. was not great, only getting better in the final episodes; thankfully this season continued on it's path of better quality as it is now actually a pretty decent show.
Since the events of Captain America: The Winter Soldier Coulson has collected a few more team mates and is running special little missions as a secret S.H.I.E.L.D. organization; which is cool to see them as this special task-force in contrast to the big shiny S.H.I.E.L.D. we all used to know. Unlike the first season, this one doesn't do the whole different-case-every-week format, I mean it does have those kinds of episodes but for the most part it's story arcs influence the events which makes it flow nicely and very entertaining as the mystery and revelations make it worth it. It of course had a mid-season break so two different story arcs which are connected but still very different entities, both of whic0h I enjoyed seeing play out.
Character wise, I loved what they did with them. Fitz & Simmons had a great arc exploring the relationship they have, Skye had a huge role in things and was the main focus of more than a few episodes, we got to see a bit more about what kind of background Melinda May had, so the original team were excellent. Three new members joined, one of which was Mack , he was good in his role moving the characters to do certain things when the plot needed; the others were Bobbi and Lance , I enjoyed those two a lot and were very well-defined characters. The only people I weren't as impressed with were Coulson, unfortunately he's quite a bit far from the fan favourite when he showed up in the movies, now because he has so many problems and worries it brings his character to a more serious and sometimes uninteresting personality. Grant Ward as well, although was a really cool character to watch, he had an odd story in the second half of the season which I was not a fan of. In the end, the second run of Agents of S.H.I.E.L.D. has vastly improved and look forward to it's future!