Prepare for a huge queue, man. I went to WinterComi and all the big circles had lines like you wouldn't believe.
Hell, prepare to be in lines pretty much half the time you're there. Should still be a blast. Bring plenty of cash too. You'll need it. Trust me.
Yup, saw it in Yuru Yuri, OreImo and Genshiken (and few other animes :)), so I know what to epxect there. Especially standing in hot, August sun. Hope this suffering gonna be totally worth it :3