Merlin - 2012
The 12th episode was great and I'm sure the next will be good too, but I can't help feeling extremely disappointed that it's the last episode (I've just now found out). The simple fact is that for the whole show they tease the audience constantly with Merlin's secret almost being discovered and then don't have his secret revealed until the final episode. I hoped to see the secret revealed, and finally see Merlin and Arthur working together, properly, but it looks like that won't be happening.
A lot of the character 'development' that occurred this season happened over the course of a single episode. The writer's for this show just did a sloppy job and made it more episodic than it needed to be. Even more damning is that they said they planned it to be a 5-season run all along source, and yet it feels like they ran out of time and crammed too much into a single season. Quite frankly, it's baffling because they're not even ending it due to bad ratings.
Mordred turned evil because a random lover appeared and broke the law - she should have at least appeared in the show at some point before, if he really loved her wouldn't he have been seeing her? This is a perfect example of something that could have been drawn out over half of the season and would have made more sense if done that way. Imagine that, perhaps, there was some drama with him missing her and having a long distance relationship via letters or something along those lines. Furthermore, they could have shown some drama with him leaving her in the beginning of the season - I'm sure that would have been difficult.
The Queen's brother randomly appears in one episode of the season to get himself killed by a floating sword, but we don't see her grieving in any subsequent episode. Even considering the fact that she was enchanted, this bugs me a lot. There's not even a single reference to her brother in any other episode. The entire sub-plot with Morganna using the Queen was a waste of time and poorly executed.
It was an entertaining show, but every time I watched it I constantly felt like it had so much potential to be better. Even as I was watching the last few episodes, I was thinking about how much I looked forward to Morganna being defeated this season and seeing a new villain in the next. Now that I know it's over for good.