It works pretty well. The main problem I encountered was decreasing the partition size to my desired size. It shrinks down to the first unmovable/locked system file.
To get round this, temporarily turn off System Restore, do the shrink and turn System Restore back on. Running a defrag may also move some of the ‘unmovable’ files.
Alternatively, you can shrink partitions by running the diskpart command from the Vista DVD, this avoids the occurrence of locked files.