Well its free which has to be something, I have it as one of my defragger tools. I also use a tool that RejZor put together Power Defragmenter a GUI interface for the contig.exe. I also use the JKDefrag GUI on occasion, all of these are free.
Now on my new system I find that with a dual core CPU, NTFS format and a relatively fats SATA II HDD, even the windows defrag on (XP Pro) is relatively fast.