Pros
Morgan Stanley employs some great people that are excellent to have in your personal network. Many of these people are very accomplished and talented. All other issues aside this can make working with people easier as it's best to respect your colleagues. The firm also has a great benefits package - salaried employees start with 4 weeks vacation which is excellent compared to other banks on the street. Compensation, 401k, and health benefits are also very good. The firm also affords some people the ability to change positions (within your business and other parts of the firm). While this is not handled as well as it is at other firms the option does exist.
Cons
This varies from business to business but the middle to senior management of some businesses have no real management skills which can lead to stagnant careers for those people who report to them. Communication is lacking and you often learn important pieces of information too late or after decisions have been made even though the decision affects you and you should have been consulted. Performance reviews are viewed by too many managers as a chore that they have to perform which in many cases makes them virtually worthless. My last performance review consisted of 5 sentences that were sloppily strung together. This ties into the general theme of not so great management skills in the middle management group.