Despite the many advanced features of ReiserFS (version 4) in 2006, Ext3 has caught up with most of those features. Furthermore, since the original author of ReiserFS can no longer continue any development effort, the file system is no longer actively being developed.
Unless you need some features that are unique to ReiserFS (such as built-in compression), it may be wiser to use one of the other file systems that are actively being developed.