I'm not in love with this show but I'll tell you right now why it's important to not get spoiled: Ward is like a million times sexier once he's evil, and like any pleasant surprise, this one hinges on being an actual surprise.
That said, the only reason his betrayal was unexpected was that it wasn't plausible in the least. His cardboard personality didn't form a basis for the payoff, his backstory was dull, and his psycho mentor wasn't the kind of guy that even another psycho would follow blindly. Ward is the very last character you'd expect to be the traitor, which is precisely why it's him, which is why it would be pathetically predictable if you're smarter than me and won't keep giving the show the benefit of the doubt.
Aside from Coulson, the rest of the cast were largely disappointing as well. Skye's arc began to get interesting but the actress still irks me. May never deviated too far from the stoic warrior archetype, which isn't one of my favorites anyway. Fitzsimmons were cute, but seemed like they were there to fill the quirky/clever non-combatant slot in the team and I can't say as I really got attached to either of them.
Characterization is usually the strongest part of Whedonverse shows, and actually, Marvel movies too, so AoS (is that the abbreviation we're using?) doesn't really feel like either. But something about it definitely started working midway through the season, and I think it was momentum. The plot was genuinely exciting and full of ridiculous twists and turns and Ward going sexy, and I can't wait to find out what happens next because I hear the second season is way better.
Honestly, momentum alone might be enough. If the show can keep going and keep tying into the films, character development will happen along the way, or maybe some cool new team members will show up. Anyway, I'm game for hanging in there just to see crazy stuff go down. Don't always have to be in love with a show; really really liking it is fine this time.