In general, the 9th Circle is not a very nice place to be (unless you are a masochist).
Some features of Treachery are:

• Residents of the 9th Circle are imprisoned in the frozen lake "Cocytus"
• The lake is guarded by Giants, so forget about escaping
• The ice of the 9th Circle is kept frozen by Lucifer's six flapping wings
• Lucifer has three faces, with three mouths, each chewing on a sinner
• Judas is in the middle mouth with his head inside
• Brutus and Cassius are in the side mouths, with their heads hanging out

• Caina (Traitors to Kin) - residents are immersed head-down in the ice
• Antenora (Traitors to Homeland) - currently under contract by George W. Bush
• Ptolomea (Traitors to Guests) - traitors are head-up in the ice, with frozen eyes
• Giudecca (Traitors to Benefactors) - residents are completely immersed in ice

Travel tips provided by Dante Alighieri
For crimes of fashion, visit Fashion Hell, 9th Circle - Treachery