Well, i am a SuSe person and i use Reiser FS so ill give some details for you all (and you better appreciate this because its a hell of a lot of typing) anyway, heres some specs:

REISERFS
Officially one of the key features of the 2.4 Kernel release, Reiser FS has been available as a kernel patch for 2.2.x SuSe kernels since SuSe Linux version 6.4. ReiserFS was designed by Hans Reiser and the namesys developmentteam. Reiser FS has proven to be a powerful alternative to the old Ext2. its key assests are better disk spave utilization, better disk access performance, and faster crash recovery, the only real drawback is that it pays alot of detail to metadata but not the data itself. Future versinos will include data journaling, both meta data and actual data, are written to the journal, as well as ordered writes.

Fast crash recovery:
using a journal to keep track of recent metadata changes makes a file system check a matter of seconds, even for huge file systems.

Better disk access performance:
for small files, you will often find that both file data and "sts_data" (inode) information are stored next to each other. they can be read using a single disk IO operation, meaning, that only one access to disk is required to retreive all the information needed.

Better disk space utilization:

in Reiser FS, all data, is organized in a structure called B*-balanced tree. the tree structure contributes in better disk space utilization as small files can be stored directly in the B*- tree leaf nodes instead of being stored elsewhere and just maintaining a pointer to the actual disk location. in addition to that, the storage is not allocated in chunks of 1 or 4 KBs, but in portions of the exact size that is needed. Another benefit lies in the dynamic allocation nodes. this keeps the FS more flexible, in contrast to traditional file systems, like Ext2 where the inode density has to be specified at file system creation time.


More specs:

Reiser FS:

File size Limit: 1 EB

File system size Limit: 16,384 GBs (16 TB)