Pros
McKesson is a relatively stable, huge company. Being in the medical field, the company should see growth over the next years. It offers a pretty good benefits package, though the medical insurance is not as awesome as you would hope. It pays for tuition and has average or slightly above average vacation/holidays. It's generally not a cutting edge technology company. Your mileage may vary. Every department at McKesson is different, and the culture varies greatly between locations. This is very true for divisions McKesson recently acquired or reorganized. The company went through a top-leadership shakeup a year or two ago. There's a little hope that the new leadership will be better, and provide a more consistent, cross-company approach to improvement.
Cons
McKesson is largely a standard bureaucratic multi-national corporation. McKesson's software division has maybe 10% of the revenue of the medical side of the company. This meas that its easy for your tiny departments accomplishments to go unnoticed outside of your team. In general, employees are treated like at any other huge company. Performance reviews are artificial, and use the GE rating system as a way for managers to leverage power, rather than offering real mentorship. Those considering working at McKesson should really get to know the existing team, the team's turnover and the team's product line and how that product line fits into McKesson global plan. You probably would want to avoid working on a dead product line (at best, as a maintenance programmer, at worse soon to be made redundant).
