Love it or hate it, it's still the ubiquitous filesystem on Unix-related systems. It might be neat to use Coda instead, but since kernels and user environments include NFS servers and clients, and the same is not true for the alternatives, we'll likely be using NFS for some time to come.
The most notable extension over RFC 1094 is that NFS Version 3 supports 64 bit file sizes and offsets. It also adds the semantic that file attributes are returned on every operation, and provides a reasonably reliable way of allowing the NFS server to do unsafe (e.g. asynchronous) writes.
NFS Version 4 Open Source Reference Implementation at University of Michigan
A Course on Implementing NFSv4 is offered by the Institute for Advanced Professional Studies (IAPF)