The bottom line with patterns is that they add value to the application architecture and the software development lifecycle. They are also great time savers and have the potential to increase the quality of most system development without increasing cost. You need to keep a few things in mind, however. First, you should not jump into patterns as a mechanism to replace a sound methodology and a sound process. Instead, patterns are able to become part of each, and in many instances there is already some pattern-oriented software architecture in place.
Patterns simply formalize the process, filling in the gaps and providing a consistent approach.
I've heard some compelling talks describing patterns as the Second Coming of software architecture. However, I've seen no evidence to validate those assertions. Patterns are simply another tool at our disposal. Second, patterns only add value if they are practiced consistently over time. Just capturing patterns for one application is hardly worth the trouble.