Can you be more specific about the type of medical app?
I have researched the appstore extensively on this subject because I have been looking for this type of app as well. I think an app called iHomeMD Pro is one of the best medical apps in the store. This app helps users to identify drugs to treat their medical conditions. If you know your diagnosed illness, you can search for drugs to treat your condition. iHomeMD Pro is particularly useful for people looking for over the counter drugs to treat common diseases. If you are proactive in your own (or family) medical/healthcare (like me), you will find this really is a handy tool to have around in your phone.
Most of other medical apps in the store are usually designed for professionals which often include too much information for my taste. I think iHomeMD Pro is the only app that provides direct reference on drug-disease relationship. This is important to me.
I have tried WebMD. I find it too overwhelming. The app is essentially a portal for their website. One has to be connected in order to use the app. Perhaps most uncomfortable aspect of the app is that, for every query, it provides "mountains of information". It is sometimes difficult to sort right information for me.
iTriage sounds depressing......
The recommended iHomeMD Pro is an interesting app. The authors designed the app to provide "straightforward" answer with concise description of the medical information. As Moon pointed out, the app provides a very useful direct drug-disease reference, which allows me to find the drugs of my interest quickly.