Until I got one:
*Disclaimer I didn't make this, but it may come in handy for future cosplay?
Seriously; the only con I have found with it is that being metal and un-insulated it cools coffee pretty fast.
Pros:
Ambidextrous - perfect for left and right handed people.
Stainless steel - Any damage you manage to do to it just add character
1 freaking liter - I can almost fit 3 bottles of beer in this thing. if you are a slow drinker just fill it with ice and plant the bottle inside it. -Great for long voyages-
Tankard design - Hollow bottom prevents the usual coffee and condensation rings on your desk say: good bye to coffee and beer coasters!
Simple finish - more artistic types can easily engrave images/designs or create other decorative wraps (if someone comes up with a way for me to get the "Ambush at skull cove" image of this thing I will lose my freaking mind).
Saves dishes - it is the only vessel I will drink from now.