I did bullets. Over in the Pre-Allo forum an Adcom, LizzyM, suggested that you list the activities as bullet points similar to what you would have on your resume and to stay away from wordy descriptions. In fact, I copied and pasted some of my work experiences directly from my resume.
I think Adcoms don't want to read too much of this in the work experience descriptions: "I worked in a ER and I remember this one time when I watched someone die and blah, blah, blah". Save all of that for your PS.