The MSN Messenger Service is Microsoft's answer to the ever-popular ICQ and AOL Instant Messenger clients. While many of its competitors have heaped feature upon feature in an attempt to be all things to all people, Microsoft has chosen to take a more streamlined, lean approach to the MSN Messenger.
As such, MSN Messenger excels at sending instant messages to other MSN and HotMail users, but doesn't offer much in terms of features beyond that. Whether this is more likely to meet your needs depends on what you're looking for in a messaging client.
The MSN Messenger interface is also far less intuitive than competing clients, and hence presents more of a learning curve to new users. For these reasons, we find it hard to recommend the Messenger over the competition; however, if you're a regular user of HotMail and/or MSN, you'll probably want to give the MSN Messenger a try.