I had one of the residents read mine. He is a senior surgery resident where I want to get in. I had him tell me first-opinion/reaction to every little part. I made small changes based on how he took some of the things I said in the statement.
Since I am applying for an osteopathic residency, I was able to tailor my statment to individual programs. Here is my favorite line of my statment:
I am incredibly impressed by the current residents at XYZ and feel their competence reflects the collective efforts of the physicians and staff at XYZ to privide quality learning opportunities in a supportive, non-threatening environment.
I think it's important to provide some sort of statment that you've given the decision a lot of thought, especially when it's a more demanding residency like surgery or IM. I also mentioned that I am AWARE of the demands and rigor of the residency, that I talked to (and listened to) everyone I could so I could make an informed decision. I also put this in:
Although a surgery residency will be rigorous, I am fortunate to have an enourmous amount of support from my husband and family, who understand that this requires a commitment from all involved.
I also mentioned that I am looking forward to serving as an example and teacher for future medical students and residents.
As for the toot-your-own-horn stuff...that's the hardest part for me. I just wrote what I felt I had shown throughout the past year (what I hope they saw me):
I feel I have shown to be a dependable, hard-working individual with a genuine desire to do things correctly.
I also went into why surgery was my specialty choice and what I get out of it, and I re-stated at the very beginning why medicine-in-general is for me. I didn't want to re-write my med-school admissions personal statement, but I wanted to mention that this field is still for me, then I tailered it down to surgery. Also, I didn't put a silver lining on everything. I admitted that rotations left me exhausted and fatigued, but the underlying excitment I felt with seeing new things each day easily made up for it, provided motivation, and made me look forward to each day.
Best of luck....and I don't think you can use the thesaurus too much!