Pros
Like many companies right now, McKesson is in a very competitive situation for their medical software. The market is saturated and opportunites are coming not from sites that have never had a particular package before, but in scavanging customers away from competitors (whether outside of McKesson or competing McKesson product). McKesson is an excellent shark in the shark tank. While some people may be concerned for their jobs, we have not seen any drop in implementations, but instead it is increasing. Company is aggressive and in this market truly amazing that it is doing well.
Cons
Overall company is fantastic to work for. Good opportunities, nice benefits, etc. The only downside to this company is you learn on the run. You go out and see an install and "poof" you are now qualified to run an install. Not good for the employees - not good for customers while employees fine tune over time. In every other way this is a good company to be in.