I've watched Agents of SHIELD from the beginning, although not always as soon as the episodes came out. Currently I'm a few episodes behind (I'm on season 5 episode 12), and I get annoyed that they seem to keep trying to circle the show back around to the same problem it has had since the beginning: The character of Daisy/Skye isn't interesting enough to be the center of the show, and the actress isn't compelling enough to justify all the other characters' deference to her.
I think both the character and actress would be fine if she were a side character or just part of the ensemble, but the show keeps trying to put her in the center. The other characters are always sacrificing for her or trying to prop her up as some kind of superstar or potential leader, but it's almost never justified by the actual events of the show or the characterization. She's a petulant child more often than she's a competent spy, an overgrown teenager more often than a savvy operator. When she's a secondary character in a storyline I actually enjoy her presence on the show, but they keep making her a key player in dramatic situations or central plot developments and I just don't think it works.
The first season of Agents of SHIELD is widely regarded as some pretty weak television, but I think they learned the wrong lesson. At the time people noticed the lack of “superhero” content and the flimsy connection to the Marvel Cinematic Universe and attributed that to Agents of SHIELD trying to be a “spy show”. I think the problem was that early Agents of SHIELD was a bad spy show, a good one with minor sci-fi or superheroic elements could have worked just fine, like it did for the first season of Agent Carter. Instead it seems to me that they've been focusing more on trying to incorporate fantastical or adventurous stuff, but I think the “premise” of the show as a team of super-spies has suffered. This is compounded by the problem that the show needs to operate within what is dictated by the plots of the movies in the MCU, which has seriously constrained SHIELD from operating as a stable, established organization.
I don't hate the show, and I occasionally even enjoy it, but I get frustrated by how often they seem to emphasize the stuff that doesn't work and de-emphasize the stuff that does.