We bought Disk Director for one reason: We had a computer running WinXP SP2 with 70GB of data on a 111GB HD in one partition and we wanted to split it into smaller partitions. So I'll be commenting on its ability to do that one thing. I haven't used it for anything else. I'll summarize here and go into detail below: The User's Guide didn't work, the program failed to work within Windows, and it was unable to split a partition, even when run from the boot disk. It was able to resize a partition when run from the boot disk.
We downloaded the program, we didn't buy it in a package, so the first thing we wanted to do was print the User's Guide. It didn't work, so we had to download the User's Guide separately from their web site. Strike One. We ran the program from within Windows, and it's really simple to understand, even in manual (non-automatic) mode. We ran through the process of splitting the drive initially into 2 partitions with some data in each; it was very simple, and after about 30 minutes, it SAID we were finished and that the disk was now 2 partitions. EXCEPT the disk was really still in exactly the same state as when we started: one partition of 111GB. Strike Two! So, we ran the program from the boot disk we had made earlier. The interface seems to be the same as with Windows, and we began the process of splitting the drive into 2 partitions. Unfortunately, when we got to the part where we told it how big to make each partition, instead of doing that, it went back to the screen where you choose what job you want to do (split, resize, merge, etc). So we tried again, choosing different sizes for the 2 partitions we wanted. Again, it went back to the aforementioned screen. No error message, no indication of any problem, it just didn't do what it was supposed to. Strike Three! Finally, I decided to try the resize function. We had 70GB of data on the drive, so I was able to resize the partition to 71GB, leaving 40gb unallocated, then used Windows control panel to create a 40GB partition. Then we went thru a similar operation to create a third partition. Disk Director may be able to do a lot of other things, I don't know, but one of its "new features" is supposed to be splitting partitions, and it absolutely failed at that.
Update: I decided to try Disk Director on another computer with another situation. This computer was running WinXP SP2, and had a non-system disk that was 250gb in one partition with no data. I wanted to split up this huge partition. I didn't even try to run Disk Director from within Windows, I went straight to the boot disk. I split the partition into two partitions, but then changed my mind and decided to merge them again. No luck. When I got to the point in the process where I told it which partitions I wanted to merge (there were only 2), it just sat and did nothing. The "commit" icon was grayed out; it wasn't an option. I tried over and over in different ways to merge those 2 partitions, and the result was the same every time; it seemed to be waiting for something. Finally, I decided to try running Disk Director from Windows. This time, I was able to merge the partitions with no problem!
So, on the first computer, the program wouldn't work at all in Windows, and was able to do only some things I tried from the boot disk. On the second computer, it performed only some operations from the boot disk, and some others from within Windows. This software can do some things it says, but it's definitely flaky and unreliable.