There are still a number of bugs with the corrective manager.
1. The tool still has trouble calculating deltas in certain situations, such as when poses overlap or when a pose is turned on in the default pose. For example, if you have a wrist pose turned on slightly when sculpting some shoulder poses, you may get a percentage of the wrist corrective baked into the shoulder correctives. In some situations it is difficult to remove the influence of one pose from another, depending on how the poses have been built. One possible solution to this is to paint blendShape weights to prevent one pose influencing certain areas, but that may cause other issues.
2. Mirroring poses does not always work correctly.
3. I recently ended up in an infinitely loop when trying to use the sculpt button on a hierarchical elbow pose. It just kept rebuilding both poses over and over again until I shut down maya.
4.. There is a memory leak when importing poses (known issue).
Some problems can be avoided by following the correct workflow, but if you are inheriting a file from another artist, it can be difficult to resolve these issues.