I am sure you will do fine. I guess some people have had bad experiences, but mine so far is very positive. I think the instructors are very supportive and available for help outside of class. Both my lab and clinical instructors are amazing, and very enthusiastic about teaching and making sure you actually learn as opposed to just pass. Like I said, some classes are just really difficult, and there is an immense amount of stress, so be prepared. Sign up for a yoga class, gym, eat healthy, and take care of yourself during the program in order to handle it all. If you already have problems in an area of your life or you are working, then it might be especially stressful, so make sure you clear out the distractions in your life and just really focus for the 15 months. I definitely thought pharmacology could have been taught in a way that was more conducive to learning, as opposed to memorization. Health assessment was also a challenging course for me and the exams were not easy. I got As in both courses, but I studied my butt off as well as went to professors for help. So it is doable if you have a good educational background, and used to a rigorous academic curriculum. I went to a very difficult undergraduate program for my first degree (uva) so I knew what it took to do well.
There is competition between students too, and some drama as it is one building with many students from different backgrounds. This especially manifests in group work, but I guess every place has it's childish drama. In my cohort, there are lots of people from Africa, so there is a racial division between the white students and the Africans and some tension there as well. I personally just go to school and come back home and study, so it's not like a campus where you actually have to be involved or talk to people outside of class.
Anyways, I would say go in with a positive attitude and excited about your chosen career and stay focus, and you will do just fine. Some classes are difficult, and while I do understand why some people would use 'horror story' to describe pharm for instance (I definitely had moments where I felt that way), I think it depends on the student's abilities and preparedness. Best of luck. :)