I cant believe how it ended.
Where is the closure? So many things were left in the open. I have to say i haven't felt this ripped off after any anime ended.
Im so disappointed 
Dude, Season three is in production and you won't be disappointed. I was scared to see an episode or two of wrapping everything up .... then I would be very disappointed. Storyline is a critical part in every anime series, book, novels, movies, etc. If the storyline sucks, the whole thing is a waste. Everything that was left, unanswered, will be shown in Season 3. Have you seen the Movie yet? You should watch it if you haven't.
I love Shakugan no Shana. Season 1 was awesome, Season 2 was a freaking blast ~ I so didn't want it to end and Season 3's going to be bigger. They're building your questions, your tensions and pushing you further to the edge to wanting to see the anime. Like Code Geass, I can't compare the both .. but it leaves you hanging, doesn't it? =) ...