350 questions. Usually 5 choices but you can get 10 or more.
Maximum possible score is probably 299 or 300, but scores above 280 are practically unheard of.
The mean was 217 this year, SD of 23.
A "good score" is defined by what you want out of your score: To be a licensed physician vs. to be a MGH-trained neurosurgeon. To meet cutoffs for residency interviews vs. to impress residency programs.