I've checked out the medication results for several different types - prescription and non-prescription, and what I see looks like it really does serve the public well without hurting traditional SEO the way other "Knowledge Graph" implementations did.
First, the left hand side, where the eye is naturally drawn, always contains the traditional 10 blue links - no proprietary Google properties at the top or within those results. The Knowledge Graph results are on the right and always in the same standardized format: a collection of types of information such as side effects, warnings, how to use, "may treat", other drugs in the same class and so on. And here's the best part - each of those standardized format sections is a blue link to a website.
Having done a lot of medicine searches in my time, I know how hard it is to find all this information in one place, so the top level "collection" that Google offers is a real service to the end user.
However, I agree with the question that lucy24 asked - will this US-centric collection of information be the same offered to search users from other countries? Only time will tell, I suppose, but some medications have very different sets of information depending on the country, including essential information such as whether a prescription is required.