Yeah, at my school pretty much as everyone here says.. 1 brief paragraph describing your undergrad accomplishments and current/past extracurriculars, 1 brief paragraph with a general synopsis of your pre-clinical years with 1-2 selected comments from your PBL, Interviewing, Physical Dx, or Patient/Doctor/Society class, followed by regurgitation of the positive/summative comments from third year rotations and first 2 rotations of 4th year ("negative comments included only if they are part of a general trend or are the only ones in the evaluation"), then summative paragraph alluding to class rank (I think we have the quartile system, but can't remember for sure) and a comment like "Student has been repeatedly praised for caring and concern for patients and her strong fund of knowledge."
The only thing that annoyed me in my Dean's Letter was their summation of my performance in pre-clinical vs. clinical years; it just wasn't accurate. Apparently, getting Honors in 2 classes (out of numerous classes) in the first 2 years, 1 a class that I had already taken at the graduate and undergraduate level, and the other class, 40% of ppl honored, and coming dangerously close to flunking several courses (P's in the rest) merits an evaluation of "she did very well in the first 2 years." Yet, I was described as "performed well" in the clinical years, where the majority of my grades were HP's (stupid surgery shelf exam brought me down to a P, and Peds just sucked) and I had super comments in Psych, FP, and Medicine. But, the letter doesn't appear to have hurt me, as I got my fair share of interviews in IM (after the Dean's Letter will be sent out), and am pretty sure that I matched at BU, Brown, UMass, Yale-New Haven, Maryland, or Maine Med. I don't mean to sound braggy or obnoxious, but am just really happy that my Dean's Letter appears to have made very little difference and wanted to quantitate for people just how little. GOOD LUCK!