I attend Miami and I think it's a good program overall. Then again, I don't have a lot of experience to compare it to. I'll give you a few of the negatives.
1. Expense - Both tuition and living expenses are much higher than a state school of comparable quality.
2. Culture shock - Be prepared to hear more Spanish than English in the hospital and in the community. You really feel like an outsider if you don't speak Spanish.
3. Poor guidance - Be prepared for little to no guidance regarding boards, class scheduling, career advising, etc. Any help you get will be from upper classmen. If you are planning on going into a competitive specialty you'll need to be preparing throughout your med school career and at Miami you are pretty much on your own.
You may find that these negatives are true of other programs. Plusses of Miami include great climate and good social atmosphere. There isn't a really competitive attitude among students. Also, Miami provides a good opportunity to experience world class programs in trauma, ophthalmology, neurosurgery, and pediatrics. You could get some great experience and research in those areas but again, you would have to seek it out yourself.
If you have any more specific questions, please repost.