Biggest Anime Disappointment?

I personally think any anime with 12 episodes has to fight to fit in a lot of story in within a very short amount of time. The Madoka manga has 3 volumes but there are many different series within it too. They split it up where the anime crammed it together. I really liked it though and it spoke to me on a different level than you it seems.

Actually I find overall that 12-13 episode series are much more fluid than 24-26 episode ones. If anything they tend to stretch series out by long pauses and unimportant scenes to make them last. They don't usually have a problem squeezing in story unless it's specifically a movie. Then yeah, they cut corners. It happens. Madoka is not a series I'd consider one that was squeezed in by any means. Now Angel Beats... yeah maybe a little squeezed. Haruhi Suzumiya was too. (Iunno why they decided to animate an even longer endless eight than in the light novel...) From someone who's pretty invested in the creation process of series (written and animated) there are signs you can usually tell when they have to squeeze things in. Like... they talk really fast or a LOT. Like in Haruhi or Bakemonogatari. Or suddenly there are developments that make less than total sense. Like in the Fate/Stay Night: Unlimited Blade Works movie. Madoka on the other hand decided to even scrunch down their series to 3 movies which is even less than 12 episodes! Clearly, they felt they had stuff they could cut back on.

All the 12 episode anime series I've seen, I felt were kinda rushed. I normally watch anime that has 24+ episodes so maybe that's why. I'm not entirely sure.

Sword Art gets better after the whole Alfheim crap arc. SAO 2 is a lot better and the Mother Rosario arc put me in tears. May I ask what you didn't like? ^.^ Because if it has anything to do with Asuna being whiny and Kirito being the modern protagonist, I can completely understand XD

I thought it was good actually. But painful to watch. Something someone should only watch ONCE. Never again. And yeah... they could have spent that time covering better arcs in the series.

I haven't started any of the Haruhi Suzumiya anime series(Isn't there multiple spin offs or something?) I wanted to but I wasn't sure if any of them are good

The first season is without doubt excellent. It's all one series, just it's not entirely chronological. The second season just kinda... went off the deep end and covered story no one cared about...