Yes and no. It concludes Touko's story, but also leaves two other character's whereabouts unknown. Sequel hook ahoy.
In case you want the spoilery details head over to my blog. :wacko:
Edit: Yeah, actually, don't do that. You'll probably read it yourself eventually and I'd hate to spoil it for you. Needless to say it's a healthy mixture of happy endings and SUPER DESPAIR, as you would expect from IG.