You never go wrong with the Original Mongolian hot pot when you go to Little Sheep. The funniest thing is that I actually discovered the Mongolian hot pot in Mongolia back in 2010 and it was a Little Sheep restaurant!
I was so happy to find out we had them here too! I can say that the food is pretty much the same as in Mongolia which renders the place very authentic.
Take the half and half broth (original and spicy) so you can alternate or separate the items you're cooking.
The service is very prompt when you ask for more, since it's an all you can eat. Some staff speak a decent English; otherwise they will rapidly send an English speaking colleague to your table.
Only warning I would give is that boiling spicy broth is smelly, so expect to have to wash your hair and clothes after visiting :)
But it's totally worth it!