I was hopeful that Mac OS X 10.5.4 would address previous versions’ data corruption issues, but it appears they still exist.
According to MacFixit, issues still exist with saving files to servers via at least AFP (are NFS or SMB affected?), system logging issues, firewall problems, and apparently Software Update is still buggy at applying binary deltas.
So, unfortunately I’m still not recommending 10.5 (Leopard) Client for folks who need to use network filesystems. If you’re using local disks only and don’t mind downloading the ‘Combo’ OS updates and applying them by hand, you’re likely to be fine and feature-wise Leopard has plenty to offer.
Hopefully 10.5.5 will finally quash the network filesystems problems, and nearly a year from release the OS will become widely useful.