Mike Lively has posted a few choice words about one of the most popular and most used design patterns out there - the Singleton.
One of the most derided, yet most loved and used patterns is the singleton pattern. Its supporters continually praise its ability to limit instantiation of objects and its opponents continually chastise its tendency to be little more than a glorified global. While programming in many ways boils down to a matter of preference (you can always find someone that agrees with you,) I thought I might as well document my opinion so that those who don't care can have one more thing to ignore.
He starts by (correctly) defining a Singleton and why, because of that definition, they are evil - they become a "global point of access". Why is that such a bad thing, you ask? Mike By their design they mask dependencies, making it harder to do future development and/or maintenance.
I personally do not see very many viable uses for singletons and I know there are many people that agree with me (google evil singletons). It's simplicity seems appealing, but they are incredibly easy to use in a damaging way. This is the danger you risk with any concept that is easy to understand and easy to abuse.