For the spicy broth, it comes in levels of spiciness from 0.5 to 5. I found level 2 plenty spicy -- anything above that might be difficult to eat. And I love spicy food!
Level 1 or 2 is hot enough. I'm partial to the lamb, special beef, and meatballs. You can get house ingredients with the mala spicy broth if you're not into tripe, intestine and such.
Also, even though the place is called a Ma La house, they do not seem to actually use any Sichuan peppercorn (hua jiao, the source of ma la flavor), so if you want it in your hot pot, bring your own!